Nope. Speed is not thrust. Thrust is how many pounds of force trying to move the airframe forward.

Change the diameter and leave the RPM the same you change the thrust.
Change the pitch and keep the RPM the same and the possible speed changes.

Pitch is the number of inches of forward travel per revolution.
An 8 inch pitch will try to move 8" per revolution.
A 6 inch pitch prop will try to move 6" per revolution.

So you see, there is much difference in speed potential between an 8" and a 6" spinning the same RPM.

When you increase the diameter, the thrust goes up if the RPM and pitch stays the same.


Assuming you could turn both props at the same RPM....
6" per revolution at 13,000 RPM would get you about 74 MPH potential.
8" per revolution at 13,000 RPM would get you about 98.5 MPH potential.
I'd call that a significant difference.

I say potential because the airframe drag may prevent that max speed from happening.