Low Mass: Two Candles lit; everything is recited; minimal to no music; absence of incense (although in the Ordinary Form incense can be used at any form of Mass); Usually said on weekdays (ferial - daily), Sunday mornings, late evenings or simply any time deemed pastoral.
High Mass: Four or Six Candles lit; everything is sung; use of incense; possible inclusion of Deacon and sub deacon; usually held late Sunday morning and other occasions during the week;
Here is a clip of Cardinal Spellman’s Mass at Yankee Stadium in 1957 wherein you see two processional crosses:
efootage.com/stock-footage/72956/Cardinal_Spellman_Anniversary_Mass/
For the low Mass of a Bishop four candles are lit; he is attended by two chaplains and two acolytes; he uses the episcopal biretta (purple in color with purple tuft or pom);
For the High Mass of a Bishop six candles are lit (seven if he is the Ordinary); he is attended by honorary deacons at the throne, the Assistant priest, the deacon and subdeacon; two masters of ceremonies, four chaplains bearing the miter, crosier, book and bugia (candle); as well as the usual servers of a Solemn Mass.
The first greeting of the bishop is “Pax Vobis”; His blessing is preceded by two versicles;
(Sit nomen Domini benedictum & Adjutorium nostrum in nomini Domini)
A Bishop may preside at a Mass wherein he wears a miter and cope and shares the duties of the celebrant; He may also sit in choir, preach and/or assist with the distribution of Holy Communion.
A bishop usually enters the church in choir dress (biretta, pectoral cross, mozetta, rochet (or surplice) and cassock) or even the cappa magna, a long cape. At the doors he venerates the crucifix and blesses the faithful with holy water. He processes in and then prays before the Blessed Sacrament. He vests either in the sacristy, a side altar and/or chapel, the throne or the faldstool. He invests in the amice, alb, cincture, pectoral cross, stole, tunicle, dalmatic, chasuble, miter and episcopal gloves.
The person holding the cross before the Pope at his election is one of the Masters of Ceremonies in choir dress; He is wearing a violet cassock over which is a surplice; This signifies he is an Honorary Prelate, the second level of Monsignori in the Latin Church. A number of priests belong to the secretariat of the Office of LIturgical Celebrations headed by Monsignor Guido Marini, the current Papal Master of Ceremonies.