"Tidy" vs "Neat"

Question

According to the dictionary definitions:

Tidy:
having everything ordered and arranged in the right place, or liking to keep things like this.

Neat:
tidy, with everything in its place.

Please let me know how the following sentences differ in meaning?

1) She likes everything neat and tidy.

2) - Your house is always very clean and tidy. How do you manage it?
- Your house is always very clean and neat. How do you manage it?

3) - My roommate is not very tidy.
- My roommate is not very neat.

I think they both mean the same thing and "tidy" is a subset of "neat". In the manner that something that is "neat" can be "tidy" too, but something that is tidy cannot always be neat. However, I cannot understand their true meanings.

Answer 1

In the ordinary description you'd say they were synonyms, but to delve a little into their history:

• neat is originally from French net (clean) and has a sense of "unadulterated", "elegant", "well proportioned". In the US (I'd guess in 50s) it has the sense of "cool" ("a neat car", "a neat piece of machinery.")

• tidy is originally from Old English tid (time) and has a sense of "timely", "ordered", "good". Still in Scotland you'll hear "a tidy sum" = "a good amount of money", "a tidy step" = "good healthy distance".

In UK we very frequently use neat and tidy as a phrase just for emphasis.