Line is single line of AC while phase refers to 1 single phase line in multi phase AC.
Line voltage is the voltage seen on the AC line, typically single phase. Line current is the current that results when that voltage is applied to a load.
If you have a 3 phase line, then each of the 3 phases (a separate wire) has it's own voltage, phase voltage. Again, if you apply a load to that phase, then phase current results.