Questions about Region Locks

[8BitRager]

I've already scoured the internet and came upon many many sites explaining the differences but never when really pertaining to games. Games and Movies are oddly enough quite different when it comes to this subject which I wasn't aware of.

Why the interest?
I want to buy WATCH_DOGS DSE and the Splinter Cell: BL 5th Freedom Edition(preferably Silver Ed.... DAMN YOU 'MURICA) for PC. They're both tagged as DVD-ROM which at first made me think they're compatible with my American machine. Great. But then I remembered that they're only sold in UK/EU so I then thought 'well may there IS a region lock'.

With all the formats:
1
2
DVD-ROM
Americas
Europe
PAL
NTSC

I'm a little confused if I'd be able to play both of these UK DVD-ROM Editions on my computer. Now, naturally an experienced collector would concern themselves with wiping the firmware off of their DVD-ROM Drive, but I'm speaking in the tense of native region locking. Would I be unable to play the DVD-ROMS that came in these UK/EU versions(Marked as DVD-ROM) on my American machine?