The "major" tractates, which are those of the Mishnah itself, are organized into six groups, called sedarim, while the minor tractates, which were not canonized in the Mishnah, stand alone.
Rabbinic literature which expounds upon such Talmudic literature may organize itself similarly (e.g. the Halachot by Alfasi), but many works follow a different structure (e.g. Mishneh Torah by Maimonides). Non-Mishnaic literature, such as Midrash, even when from the Mishnaic-era, is not organized into tractates.