Today when i saw a post of Ankur Garg their is a difference between two.Have quoted address for that.Pls refer to that and confirm the exact difference coz still doubt is coming my mind... https://www.caclubindia.com/experts/book-closure-record-date-389765.asp
I think, you should not doubtful on book closure and record date, because both are for same purpose.
As Ankur rightly said, that Book closure is made for specific purpose to fixing the record date. The Meaning of closure of register is also same for fixing the date to count the list of members as on specific date.
So, don't have any confusion on that, the whole procedure is for finalisation of number of shareholders as on specific date for this this date is fix.