Difference between the PSR and PT

by Legin
(High Wycombe, UK)

I am a beginner and I would like to know the difference between
PSR E213 (cost £75 at Woolworths)
PSR E203 (cost £90 at Woolworths) and
PT 200 (cost £70 at Woolworths)

I can't find any major difference. None of them are touch sensitive.

Can you guide me?

thanks