Points and dollars
The Nasdaq-100 is quoted at a higher level than the S&P 500 and usually moves more points in a session, while a tick is worth less on NQ ($5) than on ES ($12.50). The same idea in dollars needs a wider stop in points on NQ: plan your stop in dollars first, then turn it into points for the contract you trade.
Which one for a 50K prop account?
On a 50K evaluation with a $2,000 max loss, a common size, one NQ with a 20-point stop risks $400, and one ES with a 5-point stop risks $250: 5 and 8 losing trades before the max loss. Both are big for a 50K. Their micros, MNQ and MES, cost a tenth: they are compared in MES vs MNQ.
Neither is better in itself. Pick the chart you read best after watching both for a few sessions in your window, then keep it: switching markets resets what your journal can tell you.
Contract limits at prop firms
Firms also cap your size: on a 50K evaluation, the firms Sweep tracks allow 3 to 10 full-size contracts depending on the account, and each firm sets how micros count toward that limit. The exact limit of each account is on its firm’s rules page.
Full specs: NQ and ES. Trading hours: CME Globex: Sunday to Friday, 6:00 p.m. to 5:00 p.m. New York time, with a daily one-hour break from 5:00 to 6:00 p.m. See futures market hours in your time zone.