Lanefan
Victoria Rules
Even at low level, what you can do with Phantasmal Force (1st level spell), Improved PF (2nd level) and Spectral Force (3rd level) can get quite metal. The differences:The Illusionist (as far as I can remember, and I'm talking over 40 years ago...) had its own spell list, albeit with overlap from wizards, and the spells literally allowed you to change reality to suit your aims. They were almost unlimited in scope and allowed for immense creativity. Things like Programmed Illusion and Permanent Illusion were so flexible, and Phantasmal Killer was terrifying in the days of save or die.
PF only affects vision
IPF affects vision and hearing
Spectral affects all five senses, including touch - which means it can do damage if the recipient believes it.
With these spells 1e Illusionists also pioneered what we now know as the concentration mechanic, as those illusion spells lasted as long as you could maintain concentration (plus an extra round or two for the higher ones).
And even a simple PF can produce fun results. Our ship had just docked in a new town, and a snooty customs official had come on board with orders that nobody was to access or leave the ship until he was done. So, guessing (and hoping!) from that order that he'd be the next to use the gangplank, while the official talked to the captain my chaotic* Illusionist quietly cast PF and spent the next 15 minutes ve-ery slowly moving that gangplank three feet to the right; such that when he went to disembark - splash.
Result: official's snootiness greatly reduced for a while due to embarrassment as he's unceremoniously fished out of the harbour.
* - I've always felt a certain degree of chaos in one's outlook (both as player and character) is vital to playing an Illusionist well.
Yes, I think they and Humans were the only species that could be effective Illusionists.IIRC there was also a thing about gnomes being illusionists a lot.