Also I see #UX as a huge toolbox, where you find the proper tool to use. This makes "Implement UX of.." non-descriptive without context, or rather UX is something you can slap onto anything.
Theory (how we think we do UX) and practice are wildly different. Frustration ensues as the tools are used haphazardly in not well defined processes.
This last bit is where I feel SX coming into play. It acknowledges both project concerns and externalities, sees the broader picture still.