Google came late to social, so all the good words were taken. Facebook has friend, Twitter has follow, and LinkedIn has connect. Google+ has the less intuitive circle. A minor terminological difference? Maybe not, if you think about the four card problem.
The four card problem is a logic puzzle. You have four cards, each of which has a number on one side and a colour on another. You have to check that if the number is even, then the colour is green. The cards show 3, 8, red, and green. Which cards do you need to turn over?
Very few people get the right answer (8 and red) but you can restate the problem in equivalent terms. You’re a police officer, and need to check that the alcohol rules are being followed. Each card represents a person, with their age on one side, and what they’re drinking on the other. The cards show 14, 35, a coke, and a beer. Everyone gets this – you check the 14 year old and the beer drinker.
The point is that context matters. We’re very good at checking if someone’s cheating, and have similarly good understanding about social relationships in general. The terminology for the big 3 social sites give the functionality away. We know that friendship is symmetric (if I’m your friend, then you’re my friend) and not transitive (friends of friends are not necessarily your friends). We know that following (aka stalking) is not symmetric or transitive. And we know that connecting is symmetric, and (thanks to Six Degrees of Separation) it has a transitive aspect. No further explanation is necessary.
What about Google+? What does it mean to add someone to one of your circles? Do you get to see their stuff? Do they see yours? The name doesn’t tell you, and may even mislead – a circles of friends commonly being a group that’s all connected to each other. Does this doom the project? Probably not, but it doesn’t bode well to have your most basic operation be confusing.