not exactly. ekko is a bit more dynamic than that. The ekko player has some planning and a decision to make, which typically has to be made in advance. His ult could take him to saftey, yes, if his after image is still in a safe(er) place than he is, but it also does outrageous damage...if it does outrageous damage in a safe place(where there are no enemies) his ult is nothing more than a really fancy dash + heal. which can be good, but not worthy of "Ultimate" status. However he can be really aggressive, patience and careful to place his afterimage on top of the enemy and ult there...it is a bit more risky for sure, but the pay off is immense. Zed does not have these things. his ult does one thing...it goes in on a target, he can then go to safety but possibly does not do sufficient damage to fulfill his intended role if he escapes too quickly without doing his full combo. he also has more control over where and when all this happens, vs ekko who has to plan out everything just right and wait for his after image to be in the right location.
If ekko goes in, and gets stunned....when he is released from the stun his after image will have cought up to him and now all his plans are ruined. Zed ults in, gets stunned, needs to leave and goes back to a fixed location where his shadow stands still.
Its not quite the same.