Price, and it's not close
Plans from $19.99/mo vs $39-99/mo for HoneyBook. Every CRM feature is on every plan; the only thing fstop's tiers change is gallery storage, while HoneyBook locks core features behind higher plans. The iPhone companion app and client portal are included too. And Studio and Pro plans add client photo galleries (250 GB and 1 TB), something HoneyBook doesn't offer at all, so you can drop the separate $20-50/mo Pic-Time or Pixieset bill.