There is a slight difference. 진짜/Jinjja is typically translated to mean "real, really, reality, actuality, genuine" 정말/jeongmal - is translated to "true, truth, truly" Therefore 진짜요?/Jinjja yo? - is typically translated into "Really?/ Is this real?/ Did this really happen?" While 정말요?/jeongmal yo? - Is translated to "Is this true?/Are you telling the truth?" While their meanings are super duper close and you can change them just know that jinjja is slightly more casual talk than jeongmal which is more polite. Example: 진짜 미안해요/Jinjja mianhaeyo.. - I'm really sorry. 정말 미안해요/Jeongmal mianhaeyo - I am truly sorry.

It's not really different each other, both have same meanings: "Really"