In "Bulgaria and Macedonia" we talked about dialects, and I thought it might be interesting, if I place maps with two very basic explanations regarding the main difference between the existing dialects.
I. The first and most famous thing is the different pronounciation of a word with a я-letter, which changes to е in its plural form, according to official Bulgarian.
Example: white (sing.) = бял
white (plural) = бели
In some Eastern dialects, this substitution is ignored and people pronounce the plural form with я:
Example: white (sing.) = бял
white (plural) = бяли
In most Western dialects, the substitution is again ignored, but this time in the singular form:
Example: white (sing.) = бел
white (plural) = бели
This specific phenomenon is called the "Yat"-border i.e. there is a linguistic border, which separates the regions in Eastern and Western:
The small circles that you're seeing within the two regions are specific places, where exclusions of the general dialect rule are present.
II. The second characteristic is the different pronounciation of the ъ-sound. As you can see from the map below, this sound is changed to а, о, е or even middle-sounds, according to the region:
Feel free to dig up and post more peculiarities and characteristics of the different Bulgarian & Macedonian dialects.