As correctly said by Singer guys, S22A300B is a newer version (BX one is under archived list in Samsung site). It is marketed with the LED logo of Samsung. It has few new features such as Mega Dynamic Contrast Ratio and Magic Angle. I doubt these are available on the other version. It looks slimmer than the other ones as well. See the Samsung link for this display
here.
Following two product pages say the S22A300B is a bit expensive than the other.
S22A300B
BX2231
On Samsung site, I have noticed two things. When you go to
Find similar products you can check these things.
1. S22A300B are listed under
LED Monitor series and BX ones are listed under
Business Monitor or
LCD Monitor series. All S series ones come under LED Monitor series.
2. The BX2231 is listed under Archive (That means removed from current product list -> Means old). So the Singer salesman is right according to this.
Here is a link to a comparison.
S22A300B Vs. BX2231
As you clearly noticed, S22A300B has DVI-D/HDCP interface and BX2231 has HDMI. According to what I have understood, these interfaces are inter-portable and more importantly with no loss of video quality you can port one to the other. Read wiki
here.
So for me, both monitors are almost same but the S22 one is newer than the other. There is a newer model
S22A350H which looks latest on the LED Monitor series and the price is not that high. It has almost everything the BX has including 2 ms response time and HDMI. Just about LKR 1000+ according to the Samsung link. So check whether you can get it too.