The Online platform and the Desktop (CD/Download) platform of TurboTax are separate and distinct. In the Online platform, each purchase is good for only one federal return. But the pricing is different, too. The TurboTax FAQ below explains some of the differences between the platforms.
"What are the advantages of TurboTax CD/Download software over the Online version?"
https://ttlc.intuit.com/replies/4535178
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***