The difference between an ideal gas and a real gas is that real gases will not strictly follow the laws established for ideal gases, because of real-world characteristics.

An ideal gas can follow the formula PV=nRT
(P - pressure, V - volume, n - amount of moles, R - Avogrado constant, T - absolute temperature)

A real gas does not always follow this formula.

An ideal gas is infinitely compressible, a real gas will condense to a liquid at some pressure.

The particles of an ideal gas lose no energy to its container. A real gas conducts and radiates heat, thereby losing energy.

There is no attraction between the molecules of an ideal gas. A real gas has particle attractions.