Each increase in size numerically makes them longer physically with a corresponding smaller diverging angle. And the smaller the diverging angle; the faster speed your trains can negotiate the crossover.
The center-to-center (CTC) distance between the mainline track would be contingent on how long the diverging track is when the two diverging tracks are abutted together. Each manufacturer's turnout (switch) may and most likely will be different from one another. You may need to place a piece of flex track in-between so that the CTC distance of your mainline track is adequate enough for two passing trains running in parallel.
Other considerations are 1) how much room will you have on your layout for a crossover and 2) how long are your longest locomotives?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
What does each one accomplish that another one may not? Advantages, disadvantages, etc.
In using 2 switches to create a crossover in parallel main lines, what is the centerline distance of main lines for each number?