Looking to book PVG - BKK for early next year. The revenue Y ticket is $379 and the revenue J ticket is $459 for both Shanghai and China Eastern

I have two questions:

1) Is it worth the $80 to upgrade to J (both options are direct and $400 less than the TG Y direct price) for the ~4.25 hour flight (based on block time)?

2) Is there a difference between Shanghai and China Eastern? I know MU owns Shanghai but given how they are operating it seems like there may be differences? Can't really tell from my FT searches.

In case it's relevant, the MU flight is on an A320 and the Shanghai flight is on a 737. There is one flight with the A330 but it doesn't depart until 9pm at night and I'm looking to get on either the 1225pm (on the MU A320) or the 215pm (on the Shanghai 737)