Casual shirts cover a wider range of textures and materials than dress shirts, including linen, lightweight denim, Oxford, jersey, flannel and twill from Eton and Stenströms.
Linen is a light option for warm weather, while denim and Oxford add more texture for year-round wear. Jersey feels softer and more flexible, and flannel adds warmth in cooler weather. Button-down collars are naturally casual, while spread and cutaway collars give the shirt a cleaner shape without making it formal.
Fit varies by model, so compare chest, waist and length measurements, especially if you plan to wear the shirt untucked.