Secure Erase goes through and marks each cell as empty.
Enhanced Secure Erase generates a new public encryption key so the data is basically undecipherable. It is very fast... only a few seconds to make your data unrecoverable.
I understood that encryption wasn't added until the 320 series, the X25-M 3rd generation (the Postville Refresh). I cannot find any specifications for the X25-V which says that there is encryption. Can you provide a reference for this?
If I look at ftp://download.intel.com/newsroom/kits/ssd/pdfsX25-M_34nm_DataSheet.pdf - I do not see encryption.
So how does "marks each cell as empty" == "secure erase"??? Sounds more like a "Quick Erase" to me as all of the data still resides on the flash chips.