Both are highly effective Singapore math programs. They are more similar than they are different.

They both follow the Singapore math approach, which emphasizes the CPA (Concrete, Pictorial, Abstract) progression, centers the use of number bonds and bar models to solve word problems, and encourages mastery of mental math to gain number sense, computational fluency, and logical thinking.

If you’re trying to decide between the two programs, you may find this helpful: Dimensions or Primary? (PDF)