Lun size in VNX

Hello ,

I need to migrate 10 hosts from VMAX to VNX as the VMAX is soon going to be out of support .I will use PPME (most likely) to migrate  the data next month .

So, I would like to know  whether the size of the Luns  to be created on the target ( VNX)  should match the source lun in VMAX or it can be greater ?  Also, should I match the MBs or GBs when creating target luns in VNX . ?

Thanks !