House Sparrows look similar to Eurasian Tree Sparrows.
If you want to tell them apart, remember that Eurasian Tree Sparrows have a brown cap and House Sparrows have a grey cap.
Male and female House Sparrows look different while male and female Eurasian Tree Sparrows look similar.
In Europe you may find the Eurasian Tree Sparrow in wooded open countryside, while the House Sparrow breeds in the more urban areas.
Top: Males and females. Marken, The Netherlands, 29 August 2009
Left: A female. Landgoed Oostbroek, De Bilt, The Netherlands, 5 September 2019