model in excel: auto_open and in thisworkbook workbook_open

[SteAXA]

Someone can explain to me why when i open (right click / open) an excel model
it's execute statements in this order:
1. workbook_open (in thisworkbook)
2. workbook_activate (in thisworkbook)
3. AUTO_OPEN (in a module)
but when i use new on a model (right click / new), excel execute statements
in this order:
1. AUTO_OPEN (in a module)
2. workbook_open (in thisworkbook)
3. workbook_activate (in thisworkbook)
Thanks for each explanation, regards.