Which of the following statements are true?

[rainking]

Format drive, clean install of Yosemite and restore from time machine = install Yosemite over Mavericks?

Or

Format drive, clean install of Yosemite and restore from time machine =
Format drive, clean install of Yosemite and manually restore your applications?

 

[maflynn]

Please use the search facility, its been discussed quite a bit.

Please see these threads
Clean Install question
Clean install to a new partition.
How do I clean install Yosemite?
Clean install OS X Yosemite - what is the best way?