uBlock Origin does a more thorough job at blocking network connections [1] compared to uBlock since the former disables prefetching and the latter doesn't. [2] uBlock is also missing the per-site switches and strict domain blocking features from Origin. [3]

Personally I can't see any reason to use uBlock over uBlock Origin.

[1] https://github.com/gorhill/uBlock/releases/tag/0.9.8.2

[2] https://github.com/chrisaljoudi/uBlock/releases/tag/0.9.5.0

[3] https://github.com/chrisaljoudi/uBlock/issues/1306