The main difference between the standard and custom SE's seem to be the Maple cap/veneer and the finishes - the Customs seem to have Maple necks too. They do seem to have similar hardware - although I see the Custom 24 have PRS SE 85/15's where as the Standard has SE HFS Treble and SE Vintage Bass. I haven't checked every one to see if these are 'uniform' across all Standards and Customs but from the few I have checked, this seems to be where the differences are. I don't know if the pick-ups are radically different - maybe voiced brighter to work better with an all Mahogany construction with the Standards and the 85/15's are better with Maple cap and neck.
It seems that if you want a guitar that looks more like the US built models with many of the same colour finishes and flame maple visuals, then you buy the Custom, if its more about budget, the the Standard is the way to go. Playability and hardware seem similar enough and tone is 'subjective' anyway so you may prefer the pick-up's and construction of one over the other but both seem to have the same tuners, same trem, same necks etc so should feel and play very similarly.
Best bet would be try them out yourself and see if you think the Custom is worth spending the extra on for you. Everyone is 'different' and some will say that spending the extra to get a 10-top (around the price of an SE Custom) is worth it to them because it looks so good and others will be happy with the 'Core' because it still plays/sounds the same and still looks great anyway. Point is, only you can answer whether its better to save some money and buy a Standard or push your budget out to get the Custom. One thing most people agree on though is that at the price point - whether that's a Standard or Custom price point, the PRS SE's are very difficult t beat.
