No, they are quite different.

1. Objective Characters have structural roles and are identified by their functions.
2. The Influence character is a SUBJECTIVE character, which are identified by their points of view.

Here's a bit more background on how it all fits together...

A central concept of the Dramatica theory is that every complete story represents a model of a single human mind trying to deal with an inequity.

This occurs because in order to communicate an author must make a copy of what they have in mind and show it to the audience. This model of the author's perspective on his or her subject is called the Story Mind.

The audience examines this Story Mind from four different points of view. They are the Objective view (where we find the Objective Characters), The Main Character view (which is the subjective character who represents the audience position in the story), the Influence Character view (which is the subjective character who is trying to change the Main Character's point of view on the issues), and the Subjective view (which describes the growth of the relationship between the Main and Obstacle Characters).

The first view we will examine is from the outside looking in. This is the Objective View. From here, the audience sees characters like soldiers on a field viewed by a general on a hill overlooking the dramatic battle. There are foot soldiers, grenadiers, etc., all identified by their functions in the battle. In stories, we see these as the Protagonist, Antagonist, Sidekick, etc.

The second point of view with which an audience becomes involved with a story is for them to step into the story as if the audience were one of the players. When the audience leaves the general's hill and zooms down to stand in the shoes of one of the soldiers on the field, that soldier becomes the Main Character. The Main Character is simply the name of the player who represents the audience's position in the story.

Because Main Character is a point of view, it can be attached to any of the Objective Characters. So, in one story, the Main Character might be the Protagonist, creating the typical "hero". In another story, however, the Main Character might be the Sidekick, so that the audience observes what the Protagonist is doing without feeling like they are driving the story forward themselves. This is how things are set up in To Kill A Mockingbird, in which Atticus (the Gregory Peck part in the movie) is the Protagonist (driving the action forward) while his young daughter Scout provides the audience position in the story (which is told through her child's eyes) making her the Main Character.

Now, as the Main Character makes his or her way through the dramatic battle, he or she encounters another "soldier" blocking the path. The other soldier says, "change course!" But is it a friend trying to prevent the Main Character from walking into a mine field or an enemy trying to lure the Main Character into an ambush. This other solder is the Influence Character.

The Influence Character represents the alternative paradigm to the Main Character's existing opinions about the central issue of the story. It is their dramatic purpose in the story to force the Main Character to reconsider changing his or her long-held views. This provides the other side of the story's argument, making it a full exploration of the topic, not just a one-sided statement.

Sometimes the Influence Character is right, and sometimes wrong. And sometimes the Main Character chooses the good path and sometimes the bad one. Also, the Influence Character may not even know they have such an influence on the Main Character as to make him or her consider changing attitudes or approaches. The Influence Character can be a role model, even one on TV or from the past, whose presence or recorded works argue the alternative paradigm and influence the Main Character.

The fourth perspective is the Subjective view. This is simply a tale of the growth of the relationship between the Main and Obstacle Characters, as the Main Character is progressively influenced to change even while seeking to hold on to the tried and true. It is this view that gives a story its passionate flavor for an audience, as they watch the two "boxers" circling each other in the "ring".

When all four points of view are provided, all the principal ways of looking at a story's issues are built into the Story Mind. The Main Character is the "I" perspective for the audience - first person singular. Influence Character is "you" (for we never see things from the Obstacle's point of view, but rather look AT the Influence from the Main Character's point of view). The Subjective view is "we" as it describes the relationship between Main and Obstacle. The Objective view provides the "they" perspective, as the audience watches the Objective Characters from the outside looking in.

So, one must develop a complete set of Objective Characters. Then, one of those characters needs to be selected as the audience position in the story (which will affect the whole feel of how the battle unfolds). This will become the Main Character. Next, another Objective Character must be selected as the Influence Character. Which one will determine the complex nature of the relationship between Main and Influence, as part of their interchange will occur between their Objective Character aspects in the Objective story, and part will occur between the Subjective Character points of view in the Subjective story (Relationship Story).

Keep in mind that looking at a character as a doctor, mother, bum, or husband does NOT say anyting about whether they are a Protagonist, Antagonist or any other Objective Character. Objective Characters determine who is for something, who is against it, who acts primarily according to Reason and who with Emotion, and so on. The Mother may be the Protagonist, the Reason character, or even the Sidekick. And choosing her as the Main or Influence would add another level of complexity.

So, it is important for consistency and completeness of the argument made through the Story Mind to assign all the Objective Characters a role in your story and to make one a Main Character and one an Influence Character. But, the "feel" of your story won't truly develop until you assign the social roles these characters fulfill in your story world as well.

Often an author will wish to start with a Mother character or some other social role. Only then does the process begin of determining who is Main and Influence, and then determining what Objective Characters each represents.

How you approach the creation of the full complement of Characters and their roles is up to you. That it must be done is a result of the necessity of creating a Story Mind for the audience to both inspect and possess as the conduit of communication between author and audience.