TMS320DM6437: What’s the different between TMS320DM6437ZWT4 and TMS320DM6437ZWT7?

Hello Daniel, 

Thank you for the query. My guess is that this is the speed.

400-, 500-, 600, 660-, 700-MHz Clock Rate

Please read the note regarding the design support below

https://www.ti.com/product/TMS320DM6437

I will have to check internally on the availability of information in case you need some additional information.

Regards,

Sreenivasa