The difference between unlawful restraint and kidnapping is that kidnapping involves the abduction or taking of a person or kid of any age and then restraining them against their will and unlawful restraint just means that the person held someone prisoner against their will.
The unlawful restraint does not require someone to be abducted and you can get charged with unlawful restraint from simply holding for example your wife or girlfriend against their will.
While kidnapping requires you actually take the person and abduct them but it can also be charged along with kidnapping as criminal restraint.
The elements of unlawful restraint are those of false imprisonment which are the detention or restraint against a person's will, Unlawfulness of the detention or restraint.
The tort of false imprisonment involves an unlawful restraint on freedom of movement or personal liberty.
In law the unlawful criminal restraint is when you restrain someone and hold them against their will without legal authority to do so.
Under Law the law defines unlawful criminal restraint as knowingly and willingly holding someone, detaining someone, restraining someone without legal authority to do so.
The unlawful criminal restraint can be a form of domestic violence as well.
For example if you restrain your spouse or girlfriend or boyfriend then you could be charged with unlawful criminal restraint.
You cannot legally detain someone against their will unless they have done something to you such as breaking into your home and trying to harm you or your family.
Then in those cases you can usually hold someone against their will which some people have done until the police arrive to take over.
But you cannot just hold anyone against their will unless you have actual legal authority to do so.