"seaglider" is apparently a new word for ekranoplan. The difference is, the new ones tend not to be so enormous [1].

See e.g. https://www.regentcraft.com/seagliders/viceroy and https://www.hawaiiseaglider.org/what-is-a-seaglider

It's the same craft with a different paint job

Yes, they are Wing-in-Ground craft

1: https://en.wikipedia.org/wiki/Caspian_Sea_Monster

"Our vehicle, called a seaglider, is an all-electric, wing-in-ground-effect craft that operates within a wingspan of the water's surface and couples the speed of an airplane with the operating cost of a boat."

https://www.youtube.com/watch?v=hXE0UTHnV5g

It is a ground effect vehicle.