1-What is the difference between dialects and accents?
Very broadly speaking, differences in accent are recognised by differences in vowel sounds (and occasionally in consonant sounds).
For example, I come from Southern England and pronounce the vowel sound in bath in an almost identical way to the vowel sound in car. People from the North of England pronounce the bath vowel in an almost identical way to that in cat. That's a difference in accent.
In different dialects, people may use different words and constructions. For example, people in some parts of Scotland might say," I'll not be going the while," when I would say, "I won't be going yet". That's a difference in dialect.
2-How can the word "ajowan" be pronounced?
Sorry, I don't know the word.