Buttons vs lists
Buttons are for two or three clear actions. Lists hold more rows with a title and description. Both can continue the bot or hand off.
WhatsApp Flows
Flows are Meta-hosted forms (lead capture, appointment, survey) that open inside WhatsApp. Build the form in Meta, then attach it from a Flow node. Submissions can write variables or fire a webhook.
Limits
Your plan caps how many Flow forms and catalogs you can attach. Upgrade if you hit the cap rather than deleting production forms.