"Plot Summary:" -- There are 2 - 5 sentences per scene, so everything is rather general and therefore kind of dull. Also, apostrophes appear at random.
"Commentary" -- Really just a longer summary.
"Characters" -- Three to five sentences on each of the important characters.
"Characters Analysis" -- Extract from Characters of Shakespear's Plays (1817) by William Hazlitt (1778-1830). It's always a pleasure to read Hazlitt, but this copy has numerous typos. You can find Hazlitt on Macbeth without the typos at <http://www.library.utoronto.ca/utel/criticism/hazlittw_charsp/charsp_ch2.html>.
"Macbeth Essay" -- This is an extract from the writings of Samuel Taylor Coleridge (1772-1834). The people at Absolute Shakespeare call this extract an "Essay," but it's really a set of somewhat expanded lecture notes, and Coleridge was famous for the rambling nature of his lectures.