This is very useful information for Options trader;

The decision to trade ETF versus Index options is complicated and more dictated by your trading style, the amount you have to trade and your tax bracket. When I trade “in the money” options I prefer Index options because of no early assignment risk. But when I trade OTM options I prefer ETF options because of the smaller premiums for out of the money options, the narrow bid ask spread gets me get better fills with higher credit, plus the high liquidity of SPY in particular means greater ease of closing “out of the money” positions. Your needs may differ. Good luck trader!

Can explain notional size difference between SPX and SPY and what it means?