What’s the difference between canthopexy and canthoplasty?

I’m looking to elongate the medial canthus and the lateral canthus as well as upturn the lateral canthus to achieve (fox eye aesthetic) what’s the difference between canthoplasty and canthopexy. I read traditional canthoplasty method is unable to achieve substantial elongation and causes retraction what method is best to achieve elongation of the inner and outer canthus ?