SeaSonic PRIME Ultra Gold 750 W 80+ Gold Certified
Prime Ultra Gold was near its end of life production cycle and getting cheap(er) because of that.
They are now called PRIME GX. Not sure if anything of substance changed or just a name rebranding happened tbh, but something like the PRIME GX-850 seems to cost around 280$ CAD now.
Both your choices seem to be the exact same PSU, but one is full modular, and one isn't. Now that barely makes a difference. You must plug in the CPU and MB power connections anyway. A scenario where this isn't the case doesn't exist in the ATX world.
The semi modular PSU has less connections for peripherals etc. But other than that: it's the same thing.