Dwelly (THE Gaelic dictionary
) seems to think they're slightly different - but there are quite likely regional differences in pronunciation as well, so one person's sgurr might be another person's sgorr. I can't see that it makes a whole lot of difference!
sgòr -òir, -an, sm Sharp, steep hill rising by itself or a little, steep, precipitous height on another hill or mountain. 2 Peak, pinnacle. 3 Tail of a bank in the sea, concealed rock jutting into the sea. 4 Asperity.
sgorr -a, -an, see sgòr.
sgurr -a, -an, sm High, sharp-pointed hill. 2 Large conical hill (sgòr).