This project explains the differences between Bulgarian and Russian Cyrillic from a visual perspective. That refers to the shapes of the glyphs.
There are subtle differences in the capital letters and they refer to the shapes of letters 'Л' and 'Ф' (occasionally 'Д').
The main differences concern the lower case letters. In Russian Cyrillic they are minimized versions of the capitals. In Bulgarian Cyrillic the shapes are more rounded and have extra ascenders and descenders, just like in Latin.
The complete project will be uploaded soon.