This can be achieved in events.
There is no "else" events (like in CC).
Make an event - system: compare two values
As first value, double click system in the "objects with expressions" window and scroll down to Math-Distance (or any other expression you'd need).
Your first event check if first value is equal to second value, you'd then make another event that'd check if first value is NOT equal to second value. (to make it up for the missing "else" condition)
I understand that scripting seems sometimes like quicker to put in place then events. But on the other hand, in script, you'd lose the automatic checking of variable/parameter existence/type, visual/block organization, etc...
I understand you arrive with your knowledge and ways from a former software, but you should really learn about Construct's ways (through the tutorials, wiki, check my signature, etc...) in the first time. C2 is not GM or whatever other software.
They may have similarities, they may have the same purpose, but they are definetely different, and I think that they handle things differently.
To get familiar with construct's approach, I think you should put GM's approach "on stand by" for a while <img src="smileys/smiley1.gif" border="0" align="middle" />
(I've never used GM, so it is all assumption, but take the case of someone who is used to photoshop and arrives on GIMP. Things will be done differently in the soft, but they are both image editing tools. One just has to learn each software's way first.)