A Wi-Fi-connected monitor lets you check on your baby from your phone anywhere with signal, which is genuinely useful if you’re downstairs at a party, working from a different room, or want a grandparent to check in remotely.
A non-Wi-Fi monitor talks directly between two dedicated units over a private radio frequency, with no internet connection at all — nothing to hack, because there’s no external network path in the first place.
If you choose Wi-Fi, take the basic security steps seriously: use a strong, unique password, keep the firmware updated, and check whether the brand has had any public security disclosures before you buy.