Nope. Example: Police receive a call that a white man wearing black clothing just burgled a house on Main Street. While they are responding, they see George who is a white male wearing black clothing on Main Street. They detain George for the purpose of discovering if he committed the burglary.
Now they ask George his name and what he’s doing out on Main Street in black clothing. He says, “I’m jogging.”
At this point, is George free to leave? No, of course not. If George IS the crook, then they don’t have to just let him walk away. But do they have probable cause to believe that he robbed the house? No, of course not. All they know is that he matches the description of their potential burglary. So he’s not under arrest, but he is detained while they conduct their initial investigation.
Now, let’s say that other police officers radio our detaining officers and say, “We got the suspect over here at 123 Main Street with burglary tools and possessions from the house.” Ok, now our officers say, “Sorry for the inconvenience. Enjoy your jog!”
Or let’s say that a witness runs up and says, “That’s the guy I saw climbing out of the bedroom.” Well, now we’re building up to probable cause.
Or let’s say that George consents to a search of his person, and the cops find NO burglary tools, NO possessions, absolutely nothing to tie George to the case other than his physical description. No witnesses come forward. Well then they take down his information, name, DOB, etc. so that they’ll have it later if other information turns up that might tie him to the crime. And then they let him go.
Clear as mud?
Anyways - the point is, with a detention, you are not free to leave while the cops take a reasonable amount of time to determine if a crime has been committed, is being committed, or has just been committed. But you are not under arrest - which requires that they have probable cause to believe you committed a crime.