It is no great secret what acting is, in regards to the vocational term for those that perform dramatic roles for entertainment. But it extends much further into real life than it does on the stage. From the child pretending innocence while hiding a stolen cookie behind his back, to a soldier claiming to have no information for his interrogators, acting is an everyday part of life.
While a costume can be a major aspect of an acting performance, its purpose is very nearly the opposite of a disguise. A costume is intended to be noticed, whereas a disguise is used to prevent notice. It is not until the function of the disguise gets into the realm of impersonation that it becomes synonymous with acting. So, any amount of both skills that a person possesses are likely to benefit each other towards the success of the performance, whatever its purpose.
But the purpose of an actor's use of these skills is to bring an invented personality to believable life. Other abilities, like cosmetology, linguisitics and even storytelling add elements to a person's ability to play a role, being the benefits of make-up, language and accent improvisation, and the ability to remember lines. But these do not touch on one primary intangible that sets the great actor apart from the good one: stage presence.
Charisma, poise, voice control, resolve, sincerity and absolute, unshakable confidence all combine to create a memorability that surpasses the usual performer. Again, this memorability is one of the primary factors that sets acting apart from the more disguise-oriented aspects of these collective skills. A good actor will have several of these skills. A great actor will have all of them.
This actor will most likely be given roles where more experienced members of the troupe will be on hand to cover for his mistakes with improvised corrections. Members of the audience who have seen the plays before will most likely notice these gaffes, but have seen similar quirks in other plays, and find them to be an amusing added element. As for more day-to-day types of acting, this person could fool a friend easily enough, since they would be disposed to trust him. But had better have a good script worked our beforehand to convince a stranger of anything.
This is now the person on hand to smooth out errors on stage committed by others in the troupe. He is familiar with most popular works and has a few favorites of which he knows several parts. In everyday life, this performer can easily get past those who do not have a duty to conduct security checks or establish identity credibility. When encountering such otherwise disciplined personnel, once again, he'd best have a detailed script prepared. But he is able to perform such scripts now, without fear of forgetting his lines. There will still be times though, that this is not enough.
Employees in other aspects of theater work seek this person's advice on how they should do their jobs. Only political interference will be an obstacle to this person gaining the lead role in any theater production. Locally, this person is flaunted as the "best actor ever", and has probably been heard of in many other cities as well. Off the stage, this person can convince most anyone of anything as long as their is no contradictory evidence immediately on hand. He can even improvise his way past most unexpected situations, even if the situation is mildly suspicious. His biggest problem is, in fact, his very fame locally,since the knowledge that he is an actor will only increase suspicion. But he can usually convince people that his "similar appearance to that celebrity" is something he's been dealing with for many years now. And it is usually enough.
Even politics stay out of the way of this actor's presentations. There would be serious backlash from citizens if this person was prevented from taking the stage. But it is an understandable concern for city authorities because his performances evoke such reactions from the audience that threats of anger and grief over the unfolding of the plots onstage frequently spill into the streets as people unleash the passions the actor has generated within them. The actor also has to worry about overwrought fans reacting to the drama created on the stage. But as in everyday life, there is no one that cannot be swayed by his skill. As well with guards and criminals, only those whose devotion to, or fear of, another generates the same degree of emotional dominance have any chance of resisting this actor's charisma.