Though the clock speed of the Galaxy Y processor is 832MHz and the Explorer is only 600MHz, still the explorer is better since it is based on a better architecture.
The graphics is also better. The phone also supports adobe flash. The price difference between the two is just ~0.8k or so.
You haven't filled up the template so I don't know if you prefer any OS but as Android is flavour of the season I'll suggest you to consider to increment your budget a bit & consider these:
But the battery life will take a hit as with most of the Dual Sims so bear that in mind. The above handsets maybe available a bit cheaper at Sulekha / eBay so check them before placing an order.