MEK and Acetone are very similar, but they are not the same. There is more of a difference between them than there is a difference between (for example) xylene and tolulene. They are largely interchangeable, but there are some significant differences between them. Videoeditor noticed the difference and suggested some selective MEK use a long time ago. Both meth and pseudo are more soluble in MEK than in acetone. MEK seems more effective in dissolving some of the broken fragments of eudgragit polymers than acetone. The difference is one of degree in many ways, but in others it is one of kind. They are very definitely not the same solvent, and while they are largely interchangeable, they are not completely interchangeable.