image quality – What approximate resolution did Beta SP correspond to?

I know you can’t really say that a non-digital format such as VHS and Betacam (or LP for sound) have a resolution but it should be possible to give an rule-of-thumb estimate, shouldn’t it?

Wikipedia gives some number (300 for Beta and 340 for Beta SP) but that sounds too low doesn’t it? PAL and NTSC was 575 and 625 lines and Beta (SP) was used for that, wasn’t it? Why this discrepancy?