Yes, they're identical, it's supposed to be like that.
You can plug a phone cable or an ethernet cable into the sockets. It depends on what's connected to the other end of the cable in the cabinet in your garage as to what signals are going across the cables - if that end is connected to a router you get ethernet signals, if it's connected to your voice port you get phone signals.
There are two things you should be careful about though. First is that phones need power to ring and for the speaker and microphone to work, this comes over the line at a much higher voltage than computer signals, if you plug a computer into a phone port it can fry the network card or all of it. Secondly, while the sockets were designed to take either a computer cable (wider, 8 pin connector) or a phone cable (thinner, 4 pin connector), in real life inserting the phone connector can damage the outside pins which can mean you can't use it as a data connection later if you want to - it's better to get phone cables with an 8 pin connector on one end for plugging into the wall, and a 4 pin connector on the other for plugging into the phone handset.