Safer is a relative term. As long as you handle either nimh or lipo you should not have problems. Charge your batteries with the correct charger, at the appropriate settings recommended by the manufacturer. If you don't know what they are before you buy, contact the mfr for help.
However, if there is a problem with a nimh or lipo pack, the lipo pack is more likely to create collateral damage. An nimh cell will normally vent some gooey nasty stuff, where lipos have been known to create high heat or even fire under extreme circumstances. Though, I have seen some really nasty burns (to people) not paying attenting to how they handle thier nimh packs - but that will happen if you short out any fully charged battery.