What are the main differences between FIVB, USAV, NFHS, and NCAA volleyball rules?

Key differences include substitution limits (FIVB 6, USAV 12, NFHS 18, NCAA 15), libero serving (only NFHS allows it), point caps (only NFHS caps at 27/17), and technical timeouts (only FIVB international).

Full Explanation

The four major volleyball rulesets share most fundamental rules but differ in these key areas: (1) Substitutions: FIVB allows 6 per set, USAV allows 12, NCAA allows 15, and NFHS allows 18. (2) Libero serving: Only NFHS (high school) allows the libero to serve, but only in one rotational position per set; FIVB, USAV, and NCAA all prohibit libero serving. (3) Point caps: NFHS caps sets 1-4 at 27 points and the deciding set at 17; FIVB, USAV, and NCAA have no cap. (4) Technical timeouts: FIVB international play includes automatic Technical Timeouts at points 8 and 16 in each set; USAV, NFHS, and NCAA do not use them in standard domestic competition. (5) Roster size: FIVB international allows up to 14 players (12 + 2 liberos); NFHS allows up to 15. (6) Challenge system: FIVB has a video challenge system at elite events; NFHS does not.

Rulesets covered: FIVB/USAV/NFHS/NCAA  |  Rule Reference: FIVB Rules; USAV Domestic Regulations; NFHS Rules; NCAA Rules