Will changing bass strings from 40/60/80/100 to 45/65/85/100 require any set-up adjustments or is the difference too small to matter?

Only you can officially be the judge. You may not notice any difference at all.
Or you may notice a slight difference.
Also take into consideration that the different strings may be of greater or lesser tension.
A small truss adjustment and/or bridge adjustment may or may not be necessary after the string change.

There's a thread here that addresses a similar question:

http://club.alembicguitars.net/index.php?topic=24661.0

Are they the same brand of strings, just a heavier gauge?

J9's advice is good! You gotta just try it, unless you aren't confident making adjustments yourself. There's info here at the Alembic Club though that can help with that.

Hi Murray, I changed from D'ddario prosteels 45 -105 on my short scale bass to a slightly lighter dunlop superbrights 40 - 100. The dunlops were noticeably looser but I didn't have to change anything on the setup. I went back to the slightly heavier gauge as I prefer that bit extra resistance when plucking.

Yes, it will change, not just string stiffness but intonation, too. You'll be bothered especially if f you like low action and explore the entire neck.

Always a good idea to check set up and, especially, intonation after changing strings even if you haven't changed gauges or brand.