Pronunciation question, please help, thank you.?

This may be hard to answer as I'm not sure what language you speak natively, but yes there is a difference.
In 'Bed' and 'Head' the 'e' and the 'ea' are pronounced the same as each other, like 'eh'
In 'Bad' and 'Had' the 'a' is pronounced in the same way, like 'ah'.

Hope this helps!

"Bed" makes the eh sound, like "exit" and "bad" makes the same sound as "apple".
"Head" makes the same eh sound as "bed" and "had" makes the same sound as "apple" also.

Bed and head have the same "eh" sound. Bad and had have the same "a" sound.