Nowadays they basically cover two categories rather than one. 'Fitness' bikes tend more toward the road bike, whilst 'Comfort' bikes are more akin to the mountain bike with road tires.

I'm riding one of those 'comfort' bikes, as I've mentioned in the 50+ section. It's a bit more upright, about 5kph or thereabouts slower than a road bike and, whilst you wouldn't go on an 'A' group ride with it, it's plenty good enough for more liesurely rides. I'm planning to take it touring later in the year.

By the way. With the fatter tyres on the thing I'm chuckling every time the road bike crowd coo-ees out about a little spot of gravel on the road or somesuch