sign up 和 sign on都有签约受雇的意思？

sign on
签到
签订雇用或受雇合同
开始广播
sign on the dotted line
在虚线上签字; [转]接受既成事实
sign over
签字移交
sign up
[美口]签字应征[参加]; 签约承担义务(for)

He signed on as a sailor.
他签约受雇为船员。
sign up: to sign one's name (as to a contract) in order to obtain, do, or join something <sign up for insurance> <sign up for classes>

是的， 都有