The 7 man tent category is an odd one. Few manufacturers make a specific 7 berth model, although the Outwell are the exception.
A 7 person tent would appeal to a family or group of 5 or 6 who need a bit extra space and where a 7 berth tent would give you fairly flexible sleeping options. If you are a group of seven, then with the amount of personal baggage, you will probably be looking at 8 berth tents, to give you a little more space to play with.
As you would expect from a tent of this size, the living space is impressive, to cope with a large group or family. Headroom won’t be an issue and there will normally be a canopy or the option to add a canopy to it to create even more space for 7 people.
If you are a party of five, you could even remove one of the bedrooms to create additional storage space – a 7 man tent will essentially give you more flexibility.