Marksheet is what you have after passing your examination.
Transcript will either be:
1. Marksheet stamped by University stating that this is an official transcript
OR
2. A consolidated document which will give a gist of details for all years of the degree. E.g. If you have a 3 year BCom degree, the transcript will have marks, date of examination etc. for all three years on one transcript.
In any case, what's important is that you get the transcript in an envelope which is sealed and stamped by the University.