I have a 6110, but I have seen and used a N95 8GB.
As to whats different, camera (only 2mp compared to 5mp), no accelerometer, no wifi, and not such a large screen. Although IMO, the navigator looks better, and certainly feels a lot more robust.
The N95 (both versions) do not have any satnav software. Nokia maps is installed, and you can download the maps for free, but you have to pay for turn by turn and voice guidance.
With the 6110, you get route66 with whatever maps you need (i.e. if you buy from the UK, you get Uk and Ireland maps). You can buy any other maps from the route66 store.
I like route66, but I feel it has problems, so much so Ive bought other satnav software. But I seem to be picky, so dont let that put you off.
The 6110 and N95s can both have any symbian satnav software bought and installed for them. Theres navigon, route66 (you can buy it seperatly for the N95), navicore, garmin and others. Unfortunatly tomtom doesnt work with the internal GPS on any symbian phones, so unless you want to buy a seperate bluetooth reciever, you have to avoid it for now.
If satnav is important to you, its worth noting the 6110 has a very good nokia car holder (although pricy). It clicks in and theres a quick release. It also negates the need to plug in a cable each time.