A Low Mass simply has the priest and one or two servers. All of the prayers are spoken. There can, however, be hymns sung by the choir or congregation while the Mass is being celebrated.
A High Mass has two variations:
The Sung Mass, a.k.a. Missa Cantata, a.k.a. Simple High Mass has a priest only, without deacon and subdeacon. At a Sung Mass, all prayers are sung by priest and choir/congregation. The more common form before WWII was basically the same format as Low Mass (one priest, two servers), and no incense, but everything was sung. After WII the more common form became the Sung Mass with incense, which involved having a thurifer and MC along with the two acolytes, and possibly also torchbearers. This is the most common form of High Mass found in Latin Mass Communities today.
The other form of High Mass is the Solemn Mass, which includes three sacred ministers (celebrant, deacon, subdeacon), an MC and thurifer, two acolytes, a crucifer and torchbearers. It is common to see priests serve as deacon and subdeacon at a Solemn Mass. Often this form of celebration is referred to as a Solemn High Mass and that was its official name until the 1960 rubrics, which began to use simply Solemn Mass.
A Pontifical Solemn Mass is Mass celebrated by a bishop, and requires many more assistants, including two deacons at the throne, an assistant priest, a second MC, four attendants for the bishop (crozier, mitre, book and candle bearers) and eight (instead of six) torchbearers.