What is the difference between Shradh in Gaya versus at home?

Both are valid and both produce spiritual merit, but they differ significantly in scale: Home Shradh is the daily/monthly/annual observance performed by families for specific departed relatives on their death tithi. It maintains the ongoing relationship between descendants and ancestors. Gaya Shradh is a specialised, higher-merit ceremony performed at the supreme Pitru Tirtha specifically for: (1) Liberation of ancestors from Preta state, (2) Resolution of Pitru Dosh, (3) Sapta Pitri (seven generation) liberation, (4) Long-overdue ceremonies for ancestors who missed proper Shraddhas. The Agni Purana specifically states that a single Gaya Shradh equals a thousand home Shraddhas in merit. Most families perform Gaya Shradh once or twice in a lifetime (especially after a parent passes away) while maintaining annual home Shradh every year.