Drones are unmanned planes aimed at specific targets. They function rather like a sophisticated rocket. And we know what each costs and how they work and that they are effective.
The F-35 is being developed to be a highly mobile, sometimes virtually invisible manned fighter bomber which can carry out a variety of changing roles and missions after it is airborne.
We do not know how much each will costs. We don't know for certain how it will work and how effective it will be.
Do we need drones?
Do we need F-35s or something very much like it?
Is one an alternative for the other?