Nope. "head" is "hɜd"; "had" is "hæd". https://www.youtube.com/watch?v=UM9gPzKs1Hg

The 2 words are NOT pronounced the same. An internet search for the term 'schwa' may help you Liusu.

Most definitely different. Had= Sounds closer to "hat" Head= Sounds closer to "bed" I know of a lot of people who have difficulty with some words such as "cat/ cut", "sheet/shed" etc. It usually is because they did not drag out the sounds from certain words, making it sound clipped and curt. Maybe you need to lengthen "had" a little longer (e.g. "haa-d") and emphasise the "-ED" at the end of "head".

I believe, the two words are pronounced differently. had/hæd/,but head/hɛd/.