not necessarily...curdled is just milk that has been digested in the stomach a little bit. spit up just dribbles out of their mouth non-forcefully...vomit is forceful and your LO should "retch" a little...and it will be a LOT more fluid.
although you could have a happy spitter like me that spits up at every feeding sometimes clear, sometimes currdled, sometimes a dribble, sometimes a huge gush all over me and the floor, soaking the bib and burp rag. vomit would have more of the retch too it. in addition to the forcefulness.
My 6 week old has had vomit 3 times now and it has come out of her nose even. They have been during a feeding after about 2 oz each time (each on diff days), but it doesn't seem to bother her too much, she's never upset.
Re: spit-up vs. vomiting