Both options land you in the same outfit — the difference is fit, time and how much control you want.
You get fabric lengths for the top, bottom and dupatta, tailored to your exact measurements by a tailor of your choice. Best if fit matters most and you have tailoring access.
Ready to wear straight out of the box, cut to standard sizing. Best if you need it quickly or don't have a trusted tailor nearby.
If you're gifting or need it within a few days, buy stitched. If it's for a special occasion and fit is critical, unstitched material tailored locally usually wins.