What the terms describe
Regular usually describes a preference for the left foot forward and goofy the right. These are common boardsport terms. They express a preference, not an ability category or a reason to leave one direction out of your learning.
A twin-tip changes the comparison
A bidirectional board supports riding in different directions rather than behaving exactly like a conventional surfboard. Transferring your skating stance literally therefore does not explain all of kiting. The kite and direction of travel introduce additional tasks.
Mention previous experience
Tell the instructor if you surf, snowboard or skate and your preferred stance. This can help interpret sensations, but they must observe your response with the equipment. You do not need improvised balance tests before the lesson to obtain a definitive label.
Work on the difference between directions
If one direction feels harder, describe the specific stage: initial position, start or maintaining the run. The goal is to identify a task to practise. Comparing both directions during instruction is more useful than blaming every difficulty on being regular or goofy.
Official reference: IKO · Training videos
