I think they are similar, but Daily 3 adds the structure of Daily 5 to how the math workshop is set up. Here’s a link to a video of a teacher setting up what she calls math workshop, by using the I-charts and 10 steps to independence.
I think using the same language with as as they’ve heard with reading/writing leads to that congruence of curriculum that is so important.
https://www.thedailycafe.com/articles/setting-up-math-workshop

The biggest difference is that students are taught how to be independent and build stamina using our 10 Steps to Independence, just as with Daily 5, so the teacher can work with individuals and small groups while students are engaged in meaningful math activities. You can find the 10 Steps here: https://www.thedailycafe.com/articles/10-steps-to-teaching-and-learning-independence