1. 'Er' in American accent rolls tongue a little such as 'her' British accent short similar Thai accent.
2. 'R'in American are pronounce 'oh-er' but British accent are pronounce only 'Ah'
3. 'ar' in American accent such as care American pronounce 'ea-er' British people pronounce short care
4. 'e' in American accent like 'ei' but British accent pronounce 'ea'