wym, it changes literally everything. you literally can re allocate/ remake your character with the same level. essentially making every style of build available. here as a example
my character was initially build as a glass cannon type, speccing mostly towards Allure, strength and tech. but after fighting and losing to [REDACTED DUE TO SPOILER] i realize that the only way i could beat her is by outlasting her and spamming the Aphrodisiac debuff. something that i can't access because of my stat allocation, so,by using Respec i turned my character into a sustain type, basically allowing me to remodify the stats without having to restart the level grind all over again. allowing me to change into a will power/magic based build to defeat the boss from before.
hope that helps :D