Difference between Dell Precision 3620 MT and 3420 MT

Hi!

In what difference between Dell Precision 3620 MT Xeon E3-1225v5 and 3420 MT Xeon E3-1225v5 , except the sizes of the case and the number of internal sockets?

Components of the main board and video identical?

Our software vendor tested his software on 3420 MT but the sizes and configuration 3620 MT suit us more.

Thank you for answer and a`m sorry fo my bad english.