There are two separate exercises:
45 Degree Barbell Row (Yates Row) - hits the lats and biceps quite well, doesn't touch the floor, easier on the lower back, easier to learn, can use more weight, easier to use body english and cheat. In my experience this should be essentially equal in strength to your bench press for good muscle balance
90 Degree Barbell Row - hits more mid back, traps, rear delts, rhomboids, touches floor every rep. Essentially looks like a bench press facing the floor. Use less weight, more stress on the lower back, in my experience this exercise carries a higher risk than the 45 degree row.
Both are great and can be used in an exercise program, it isn't a matter of right or wrong but just pros and cons of each one.