Why SD card is less durable than internal storage in smart phones?
Is the internal storage made by different technology? 


No, it is often just embedded MMC - which is technically equal to a SD card, just in a BGA package for soldering onto a PCB.

Note that there are very bad quality SD cards on the market, which do not tolerate much writing. I managed to break two el cheapo noname cards in weeks, without writing that much data with my microcontroller. 

Using SWAP on SD will break even good cards with wear leveling rather quickly. Flash memory allows only a limited amount of write cycles, and swapping can cause a lot of writes.