Which should you choose?
Pick Runway Gen-4.5 for high-quality production work and mature tooling. Pick Seedance 2.0 Fast for reference-heavy clips with native audio. Use the same prompt brief, aspect ratio and acceptance rubric across both.
Cost at production volume
At 1,000 ten-second generations, Runway Gen-4.5 is about $1200 and Seedance 2.0 Fast is about $2419, before retries and ancillary fees.
Method
We prioritize first-party API pricing and explicitly label resolution and audio. Speed descriptions are directional unless the provider publishes a repeatable benchmark.