I Tested Runway Against Grammarly for Real Work, Not Demos

I hate doing anything twice, so I fed the same input to Runway and Grammarly and counted what broke.

Runway generates a short promo from a text prompt alone. What I didn't expect: has a toolkit (mask, motion) that covers most social needs

Grammarly takes the other lane: rewrites a cold email into something a human would actually reply to. works in the browser so it follows you across every text box

Neither is clean, though. Runway faces morph if the clip runs long. And Grammarly it flags correct sentences as errors when the context is technical.

Here's who should actually pick which.

Pick Runway if you're a social creator who needs motion without a shoot. Pick Grammarly if you're a non-native or rushed writer who wants a second pass before send. I landed on Runway for daily use and kept Grammarly for the one thing it does that the other can't.