Why do you want to migrate? Do you have any issues with Hostgator?
If yes, you can migrate to Bluehost and check the hosting. You have 30 days money-back guarantee too. Test and verify with your site.
You can find many tutorials on youtube about migration.
Please find them.
Honestly, i dont think so. But i read on google that you can loose some graphic data and can get some 404 errors