Nu-Disco emerged in the early 2000s as a contemporary, mostly electronic interpretation of disco music.
Most nu-disco has no named sub-style or clearly defining characteristics, other than being rhythmically disco-based and not fitting into any other genre.
Nu-Disco often makes use of the standard disco rhythm (kick drum on every beat and a closed hi-hat on every eighth note), rather than the "high-energy" disco rhythm which underpins much house music (same kick but with an open hi-hat on the "off beat", i.e. every eighth note in between). It may also incorporate 1980s Italo Disco-style synths & drum machines.
Some nu-disco is simply re-edits (sometimes with added effects) of original-era disco & boogie tracks. Some nu-disco is in a slowed-down "slow motion"/"cosmic" style. Some is quite fast and "hard" and can be more precisely described as "electro-disco" or "electro-house" depending on its resemblance to electro, electroclash, disco, and house. Some nu-disco has a very retro, Italo-Disco inspired sound but probably should not be tagged as Italo-Disco.