Originally Posted by
MR.TeachFreak
There can be depending on the bar. A deadlift bar has more whip so bends more when you lift and thus you are not lifting all the weight immediately. So in that case there can be a difference between that and a powerbar which are generally very stiff. Some people can have a reasonable difference between a deadlift bar and powerbar PR. I would only use a deadlift bar if I entered a strongman contest using one. I personally will usually deadlift 10-15 lbs less on a axle, which is solid, then on the normal bars at my gym.
Bench and squat bars, from my understanding, are made to handle much more weight then normal bars and sometimes have extended sleeve length so you can comfortably fit more plates on plus a beefier clip.
Then, of course, you can get into specialty bars like the SSB or a cambered bar which can have a measurable effect on your training. SSB puts the weight more similar to a front squat while a cambered bar puts the weight much lower and acts kind of like a pendulum(?) when you squat, forcing you to stay tight in your lowerback and core.