Difference between 硕士英语A班 and 工程硕士英语
硕士 means the college degree in modern Chinese, nothing else, unlike the English word Master.

工程硕士 is Master of Engineering. 

硕士英语 is the English course for a student who is pursuing a master's degree. 

班 is an assembly in which people study and take exams together, usually consisting of 30 or more people.

So to conclude:

工程硕士英语 is the English course in a college aimed at Chinese M.Eng students who usually have no more than 5000 English words in command. After the course you'll gain an additional 1000 vocabularies as well as a few reading, writing, and translating skills. It's a class focused on basic English skill, not necessarily related to engineering.

硕士英语A班 is an assembly of M.Eng students taking an English course, this group is labelled as A. There might be B, C, D, etc., but A usually doesn't mean it's better or prioritized; These are just labels.