Difference between 90-005 and 90-009?

The difference between the 90-005 and 90-009 is subtle, but important. You can see that each lock has a different style locking tab, which is what physically secures it in place and locks the window.

In the case of the 90-009, the tab has a crescent-shaped indent. Its purpose is to allow it to lock into a keeper. The 90-005, meanwhile, has a flat tab. Its purpose is to fit under the glazing of the top sash. They both do the same job, but in different ways and for different style windows.

Hopefully this information has been helpful, but please let me know if you need anything else.