It gets rendered as 60i, and each source clip will undergo frame rate conversion. Generally, this will mean resampling (unless you've disabled it on some clips), which means frame / field blending. It will look different than pulldown. Also, titles, FX, and transitions will run at 60i instead of 24p. However, for a single 24p clip with resample disabled, it will do something that will look just like pulldown, just due to how the frames are being pulled without resampling. However, it will render slower than rendering 24p with pulldown, and the output file won't be marked as having pulldown, so if you bring it back into Vegas, it will be 60i and not 24p.
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