sign up和sign in二者有何区别?

如果是网站,sign up 是注册,sign in 是登录

sign up
v.
签约参加工作, 签约雇用
sign in
v.
签到, 记录到达时间, 签收

sign up
v.
签约参加工作, 签约雇用
例句：
Sign up more workers to boost production
再签约雇用工人以促进生产
But that sign prices slashed by up to 25%.
但那个牌子上写着削价百分之二十五。
Sign up for a set o...

sign up
v.
签约参加工作, 签约雇用
sign in
v.
签到, 记录到达时间, 签收

sign up 报名，签约参加工作, 签约雇用
sign in：注册账户。