Yes, although 'in the loop' perhaps suggests more people.

They are very similar, but there are situations where I would say ‘posted’ but not ‘in the loop’. ‘In the loop’ implies a sort of involvement, whereas ‘posted’ just talks about a transfer of information. So if a group of people are making plans that affect others, you would want to keep them posted or in the loop. But if I were merely curious about something, only ‘posted’ sounds right.

Hey Ali! Both expressions have same meaning just that, keep me posted is commonly used. Best regards 😊

Both have the same meaning however “keep me in the loop” is more casual.

They are the same