One of the biggest changes were that you could only be cleared for 7 actions:
Cleared for take-off
Cleared to land
Cleared for the approach
Cleared for SID
Cleared for STAR
Re-cleared from flightplan route
Re-cleared from flight plan altitude
(the last 2 are because when you ask for clearance before start, you are actually cleared for 3 things: Cleared XXX to YYY FL280 (implies flightplan route and altitude) off RWY xx via the EXAMP 7A departure)
All other ATC directions are "Instructions", not "Clearances".
Clearances have to be read back in full.