The green team, Nvidia, has been doing a lot of renaming of their video cards for a long time now. This time around Nvidia has dwelt on renaming the old Geforce GT 520 to the more recent Geforce GT 620. There are however slight changes on the 6 series model. One of the most distinct change is that the GT 620 memory has been reduced considerably by half making it 512/1024mb instead of the previous 1024/2048mb. Though, this won't really matter on some applications. But beneath these setbacks, the newer version GT 620 supports Open GL 4.2 from the 4.1 of the older 5 series counterpart.
The 510 videocard will also be replaced with the latest Geforce 605. On the downside of this, the graphics clockspeed is reduced from 810 to 523 MHz; processor clockspeed has been decreased also making it to only 1026 MHz from the older 1620 MHz. The bright side on this is that the newer models now consume lesser power and are now based on the Kepler architecture, which is the same design from the GTX 680 class.
The good news is that the Geforce GT 620 and 605 won't make it to retail and would only be limited to OEM production.
Rebranded as usual