Why JT65 is a multi-frequency-shift-keying mode: each symbol is one of 65 audio tones (a sync tone plus 64 data tones) keyed one at a time into an SSB transmitter, so the RF output is a series of shifted single tones. Because the tone shifting is done at audio and fed through SSB, it is described as multitone AFSK. The constant-envelope, narrow, slow (about 0.37 second per symbol) signal is what lets JT65 decode EME and other signals well below the noise floor.
Watch out PSK is the usual trap because of PSK31 and because both are weak-signal keyboard modes, but PSK varies the carrier phase while JT65 varies frequency; RTTY is only two-tone FSK with Baudot code, and QAM mixes amplitude and phase and is used in commercial high-rate data links, not in weak-signal amateur work.
JT65: the 65 is the tone count. 65 tones means many tones, so multitone AFSK, not phase shifting.