Distinguishing p from o xylene

para substituted rings give very easily recognizable patterns.

2 for each CH3 group, 2 different peaks for the 2 different types of hydrogens in the ring.

I'm not sure. And my question has to do with differentiating the ortho and para

The xylenes are frequently used to exemplify the effects of symmetry in NMR spectra. How many peaks would you predict for each isomer?

There are two sharp singlets for p-xylene, 4H:6H. The ortho and meta isomers have single peaks for the CH3 groups. Why?

Meta is a doublet between the two methyl groups.  Why?