You can change most of the Look and Feel of FluxBB. While some modifications like changing the color scheme or even the complete style of your forum up to a specific limit only require a single click, other enhancements may require massive sourcecode changes.
A FluxBB Style is a combination of CSS-files (and images if required) which can be installed without changing any core files. All PunBB styles are compatible with FluxBB 1.2.X.
To install modifications (mods) you have to alter FluxBB core files. All PunBB mods are compatible with FluxBB 1.2.X.
Plugins are modules for the FluxBB admin interface that can be installed by simply dropping the plugin file in a special FluxBB folder. All PunBB plugins are compatible with FluxBB 1.2.X.