The larger line is the supply line and the smaller is the return line. Both of them, along with a third vapor line travel under the car and go to the fuel tank.
Personally, I would not repair a nylon fuel line. With the pressures found in modern fuel injection systems, I feel that it's only a matter of time before the repair will fail. That's not to say that repairs are not made. I have a
steel repair section of fuel line on my 90 and it's working fine. With that being said, there are a couple of distributors of nylon fuel line repair hardware. One is
http://ken-co.com/default.htm. The problem is that they do not do consumer sales. Only garages and dealers. I suppose if you were self imployed in a related industry (or know someone who is), you could open an account and order the parts you need. I don't know if minimum orders apply. There is a link for consumers to locate a dealer... you can also try that.