拘束 has two uses: (1) as an adjective meaning 'uncomfortable/stiff' in social situations (别拘束), and (2) as a verb meaning 'to restrict/constrain' (拘束自由). The adjective use is more common in daily life.
memory
Both characters mean 'restrain/bind' - imagine being tied up (束) and held back (拘), making you feel stiff and awkward at a party.
