neat = tidy They are synonyms. They are both used to mean 'in order'and 'carefully done or arranged' 'I like everything to be neat and tidy.' 'Keep your room neat and clean.' 'He's a neat person= he likes to keep things tidy and in order.' 'You should dress neatly when you appear in public.' I want to add an idiom that means 'neat and tidy; done or arranged very accurately or carefully'. It is 'just so': 'Her hair is always just so.' 'He liked polishing the furniture and making everything just so.'

'neat' and 'tidy' (you can also include 'clean') are synonymous. I don't see any significant difference between these words, only that 'neat' are mostly used in referring to a person while 'tidy' to a thing or place. in american english, I think "neat" is more often used rather than "tidy". :)

Neat refers to: 1.Clean or organized "her neat dress"; "a neat room. 2.Showing care in execution "neat homework"; "neat handwriting" 3.Free from what is tawdry or unbecoming "a neat style"; "a neat set of rules"; "she hated to have her neat plans upset" 4.Free from clumsiness; precisely or deftly executed "the neat exactness of the surgeon's knife" 5.Very good "a neat sports car" 6.Without water "took his whiskey neat" Tidy refers to: 1.Marked by order and cleanliness in appearance or habits "a tidy person"; "a tidy house"; "a tidy mind" 2.(of hair) neat and tidy 3.Large in amount or extent or degree "a tidy sum of money" cowboy...