Erase takes the address off your mailbox and leaves the mail in it for the next resident to use. Secure erase opens it and scritches off all the words from your mail. Takes time though.

When you normally delete a file, it doesn’t actually delete it, to save time it just marks the space as free, so any new files can be written into that part of your drive.

But the actual data just remains there until a new file is written to the storage.

SecureErase does the second part without making an actual file.

Normal delete:

File: 01010101 -> no file:01010101

Secure erase:

File: 01010101 -> no file:00000000