A Content ID claim is YouTube's notification that you might be using copyright-protected content. Like a copyright takedown, it could be disputed and retracted but will not result in a strike. However, the copyright claimant might utilize your video for monetization, collecting viewers' data, or the claimant may choose to block it from certain countries.
A copyright takedown is a legal procedure that a copyright owner initiates. It will result in a copyright strike (which can be disputed and retracted). Three consecutive strikes within 90 days will result in the termination of your account/channel.
You can find more information on YouTube's Help page.
Our music library contains many tracks without Content ID or PRO tags. You can find out if a track has any restrictions in the tag section on the right side from each track: