As for the actual structure of the play usually the performance would begin with one or two of the characters the chorus then would enter singing and dancing, then there would be dialogue. This would usually just continue alternating until the end of the play, the chorus exits singing a song which generally offers words of knowledge connected to the deeds and consequences of the play. This is almost identical to what we call modern day musicals. Usually they begin with a character having a self observation or some sort of small monologue that introduces us to the show then they begin to sing.
Quite a big difference between modern day and ancient Greek theatre is that back then they only had 3 actors no matter the requirement for the performance and the chorus. Very unlike today’s drams which has usually a 10+ cast. One of the largest cats ever in a film is probably in the film ‘Ghandi’ which had over 300 000 extras in the funeral scene. Another large cast production is ‘Lord of the Rings: return of the king’ had around 20 000 extras participating in the battle scenes. Another dissimilarity between modern and ancient is that the Greeks only had Male actors, whereas today the entertainment industry has men and women. However it is more common for the men to be working behind the scenes e.g. directors, stage crew, paparazzi. 77% of Oscar winners are male which is saying something that it is still not equal.
The three genres of drama were comedy, satyr plays, and most important of all, tragedy.