Question about CST and Sonnet

Could anyone tell me that CST is similar to Sonnet, they also are EM simuatlion software?

If no, what functions could Sonnet provide us?

Sonnet is a 2.5D simulator and CST is a 3D simulator , just like the Ansoft designer and HFSS. Sonnet is used to simulate the planar circuit such as microstrip , CPW, strpline circuit etc. and I think it is very accurate and fast cause I have used it for a long time .