"Price disparity" refers to a difference or gap in prices between different products or markets. It means that the same product or service can be sold at various prices depending on the location, time, or other factors. Full definition
Because ETFs trade on a stock exchange, there is the potential for price disparities to develop between the trading price of the ETF shares and the trading price of the underlying securities. (us.etrade.com)
Large price disparities are particularly likely to happen if an ETF's last trade occurs well before the market close. (fidelity.com)