The difference to me is that Depot is giving you what is effectively a dedicated build machine. That machine can take advantage of local BuildKit caching.
With Cloud Build, you need to use —-cache-from and other amendments to leverage remote caching. (And I believe that caching multi-stage builds require you to explicitly bush and push every stage.)
With Depot, you should in theory get all of that caching “for free”. You can also take advantage of things like BuildKit cache mounts (local directories on the host machine to cache, e.g., pip install artifacts) which AFAIK can’t be done with Cloud Build.
(No affiliation with Depot but I have played around with it.)
With Cloud Build, you need to use —-cache-from and other amendments to leverage remote caching. (And I believe that caching multi-stage builds require you to explicitly bush and push every stage.)
With Depot, you should in theory get all of that caching “for free”. You can also take advantage of things like BuildKit cache mounts (local directories on the host machine to cache, e.g., pip install artifacts) which AFAIK can’t be done with Cloud Build.
(No affiliation with Depot but I have played around with it.)