Validate vs dry-run: What are the differences and when to use them?

[jtryan0601]

I'm curious about these commands. What are the differences and when to use which? Also, which one has better performance?
a) sf project deploy start --dry-run
b) sf project deploy validate

[mshanemc]

sf project deploy validate is meant as a precursor to sf project deploy quick. You're wanting to a quick-deploy to production and you want a deployId that will accomplish that.

sf project deploy start --dry-run is meant for all other scenarios and is much more flexible.