工卡(EAD)employment authorization documents
OPT, DACA, Advance Parole…etc
基本上唔係PR/citizen但又可以係到返工既人都會有一張咁既work permit,同green card一樣樣只不過係紅卡
SSN( social security number)
只會出比PR, citizen, temporary resident (F1, H1B之類)
用黎track你income同benefits
係兩樣野但有工卡既人就會有SSN