Which is the best, chemical engineering or civil engineering?

It is very near to impossible to distinguish between these two streams as they have very little academic relationship, choosing civil or chemical engineering career depends on your interest, I'll share my personal experiance hope it may help you: here in mumbai university we have 1st year of engineering course is same , but from 2nd year

What is the difference between undergrad school and graduate school?

Ryan has a great answer on the degree aspect.On the detailed aspect, undergrad usually does not require a research at the end of it (many college do this to ramp the difficulty for whatever reason, though), while a grad requires a research culminating in a theses