celebrity often wears a disguise when he wishes to go unnoticed. In order to make sure that nobody recognises him, he makes a conscious attempt to alter his looks. He may decide to sport a wig, wear the kind of clothes that he normally doesn't, etc. By changing his appearance, he is pretending to be someone that he is not. People usually wear a disguise in order to fool or trick others. *In many of our old movies, the King always used to disguise himself as a beggar. The word ‘guise' has a negative connotation as well: it suggests that the individual is pretending to be something that he is not. In this case, he doesn't necessarily alter his appearance; he changes his manner or behaviour. He puts on a front. *She got him to tell her all his secrets under the guise of friendship. http://www.hindu.com/edu/2010/07/13/stories/2010071351651403.htm

Guise means an artful or simulated semblance "under the guise of friendship he betrayed them" While Disguise means 1.An outward semblance that misrepresents the true nature of something "the theatrical notion of disguise is always associated with catastrophe in his stories" 2.Any attire that modifies the appearance in order to conceal the wearer's identity 3.The act of concealing the identity of something by modifying its appearance "he is a master of disguise" And as to Verb it means to make unrecognizable "We disguised our faces before robbing the bank" cowboy...

Guise is generally used to describe a behavior where disguise is generally about appearance, clothing etc. Try googling it. I think it's a common question.