Why would the last one upgrade visually when you haven't upgraded it points-wise? Sorry, I mixed up the words. They are ultimate. But about PF Ez.
Let's compare it to Final Boss Veigar, a great example of a legendary skin.
MODEL
FBV: New model for Veigar. New animations for his staff, eyes, and cape.
PFEz: Four new models for Ez.
PARTICLES
FBV: New particles for his abilities, joke, auto, recall, spawn, death, and Q kill.
PFEz: New particles for Ez, abilities, auto, recall, joke, taunt, dance, kill, ult level up.
ANIMATIONS
FBV: New animations for abilities, auto, joke, recall, death, spawn, walk, capture, and idle.
PFEz: New animations for abilities, auto, joke, recall, walk, capture, two new 'fly' animations for walking.
SOUNDS
FBV: New sounds for abilities, auto, recall, death, respawn, Q kill. New voice-over, several new quotes.
PFEz: New sounds for abiliies, auto, recall, joke, taunt, ability level up, match beginning. New voice-over for Ez, new voice-over for his suit; many new quotes.
OTHER
PFEz: Banner, summoner, in-game portrait
Although legendary skins provide a lot, PFEz definitely provides significantly more.