It's a massive difference. Consider linkedin vs national UK login.
The later one guarantees the identity: full name, date of birth, address, verified phone number, last taxable income, etc...
It allows to request government benefits or open a bank account online, because the identity is guaranteed. There is a real verified person behind the account. (corollary: you will be in troubles if somebody gets credit cards under your UK identity).
On the other hand, it's not great if that identity is required to apply to a job. The company can see your passport after they hire you. There is no need for every job board and recruiter and company to systematically get all your personal information in advance.
The later one guarantees the identity: full name, date of birth, address, verified phone number, last taxable income, etc...
It allows to request government benefits or open a bank account online, because the identity is guaranteed. There is a real verified person behind the account. (corollary: you will be in troubles if somebody gets credit cards under your UK identity).
On the other hand, it's not great if that identity is required to apply to a job. The company can see your passport after they hire you. There is no need for every job board and recruiter and company to systematically get all your personal information in advance.