Cyberpunk generally has a high focus on the punk aspect. I.E, anti-authoritarian, personal freedom, anti-hierarchy.

Steampunk has punk at the end purely because it's a riff on the word Cyberpunk, not because it retains any inherent anti-authoritarian punk-ness. It's more so just a label shorthand for an aesthetic and rough technological level. Dieselpunk does the same thing, using punk not to signify actual punk ideals, but instead uses it as shorthand for 'aesthetic'.

Solarpunk retains the punk aspect of Cyberpunk, but instead of dystopia, imagines a more utopic vision of punks succeeding against the corporations/governments/hierarchies, which is achieved through community building, a DIY ethos, prefiguration, and an appropriate use of technology.