Hey,
Both BA Honours in Political Science and BA in Political Science is more or less similar if we talk generally.
See,in BA Honours Political Science you get a major degree in Political Science. While if you are pusuing graduation in BA Programme,you will need to study a set of subjects in Humanities.
Hope this helps.
Good luck.

The major difference is, in B.A (H) you would be studying particular specialisation papers (pol sci.) in the third year whereas BA would be common and there is no core specialization. Also, if you are interested in DU then in DU admissions are done on the basis of 12th merit and the cut off varies college and course wise so to get a rough idea about the same you can go through the below link-

DU Cut off

Good Luck!!!