I like to learn more about the difference between BMX flip flops and fixed/free flip flops.

I am considering a suicide hub on my 27” wheel or getting a (under $40) Redline BMX flip flop 20” wheel and build a new 27” or 700c wheel out of it on a frame with 130 mm dropout.

Do fixed/free flip flops have same diameters on both side, just a matter of left handed thread for the track cog and right hand thread for freewheel?

What about BMX flip flop, my impression is both sides are left hand (?) threads of different diameters? The seller says both sides appear to be the same diameter. Do they make a fixed/free flip flop for BMX? Are the 14 mm axle a different size than what I would need on the road wheel?

Do track cogs have left handed threads or it doesn’t matter as it’ll go on both left and right handed threads just depending on which direction you turn it?