The iDRAC Enterprise board is the same part number for those servers, but it's a simple pass-through module. As for iDRAC firmware, it's not always a clear cut answer. Some of them are different, not necessarily all of them. Generally speaking, you'll be best served pulling the iDRAC firmware for your system from it's respective page.
We have 3 different models of older Dell servers in use, all of which have the iDrac6 installed.  Only one of those models (R310 had available iDrac firmware 2.92 for the recent vulnerability ([URL] I was able to upload the firmware for the model where it was available to another iDrac for a server that did not have it available.  It staged for upgrade with the correct old and new versions.  However, this seemed a little sketchy since it was not from the support downloads for this model and svc tag.  So, I did not proceed. The model with the available update was R310.  We also have R415 and R815 models.  Are all iDracs of a particular major version the same?  Surely not.
Is one iDrac 6 the same as another iDrac 6