No, they don't sound the same. I've used the ER4S for over 6 years, and the ER4SR for a few months. To my ears, my main takeaways are
- ER4S is a little more pronounced/forward, where the ER4SR takes a few steps back in its presentation (not to be confused with increased sound stage depth)
- ER4S is a little easier to drive
- ER4S has mids forward a little more where the ER4SR is a bit more ruler-flat
- ER4SR has better precision with instrument separation and not getting muddled during high-intensity passages, where the ER4S can occasionally sound a little "smoothed over"
Overall I very slightly prefer the ER4S but I think that's 90% a matter of the music I listen to. I still taken time to use my ER4SR for multiple hours every week.
I would actually say the ER2SE sounds closer to the ER4SR, than the ER4S does.