Well, that depends on how technical you want to get with the definitions, and what you mean by town and by city.
En stad refers to a city. For small cities, you can say småstad if you want to point out that it's small. The other way around with storstad (lit. "big city") works as well.
En by is a (little) village, but rarely used these days. It's very rural in its meaning.
We also have the word tätort which translates quite well to conurbanation. It's defined by Statistics Sweden as an area with as least 200 inhabitants, no more than 200 meters between houses and no more than 50 per cent summer houses.
Thank you! Here in Britain 'city' is a specific term for the largest settlements (or, if you get technical, somewhere officially granted city status, usually with a Cathedral or University). Towns can be big, but they are sort of the mid-point between villages and cities - I had no idea whether or not the same specifics apply in other countries, so thank you!
As I understand it (growing up in New England), a town and city are not necessarily demarked by population, but by system of government, so it is possible to have a city that is smaller than a town.
The primary (if not only) difference, is that a town has a board of selectman, and a city has a mayor.
I chuckle to myself when I hear people talking about their "small towns" with populations of over 30,000, while there is only one city (or town) within an hour's drive from me with a population over 15,000 (It boasts 23,000).
No, sydlig is a word in Swedish as well. For instance:
- En sydlig vind sveper över Sverige = A south wind is sweeping over Sweden
- Huset är sydligt beläget = The house is in a southward location
The differences are far from obvious, but the general rules are these:
- syd or söder is a noun (or sometimes an adverb - you can probably skip that sense)
- södra is an adjective, but it only really works with plurals and definites
- sydlig is an adjective, it works with everything using normal patterns but it's less common and typically less idiomatic