Learn English – What’s the difference between ‘why would you do that’ and ‘why did you do that’

I thought that site explained it pretty well, but I'll rephrase it just in case:..

We use prefer to say we like one thing or activity more than another. We can use a prepositional phrase with to when we compare two things or actions:

I prefer tea to coffee.

We prefer going by ferry to flying.

We use would prefer or ’d prefer, followed by a to-infinitive or a noun, to talk about present and future preferences:

I’d prefer to go by myself.

Would you prefer a quieter restaurant?

She’d prefer not to drive at night.

So, 'I prefer' means 'I like x more than y.' The comparison can be implied to include all possible options in that category by omitting 'more than y,' as in your example:

She prefers to drink tea.

This means that, as a general guideline, she would rather drink tea than any other beverage. Context can also imply a more specific comparison:

Jim: Have you been to Coffee Unlimited? They have really great coffee.

Sue: No, I prefer tea.

Given the context of coffee, this means that she, as a general guideline, prefers tea over coffee.

We use 'would prefer' to specify a specific occasion:

She would prefer to drink tea.

This means that, in this particular instance, she would rather drink tea than a different beverage. This does not imply that she always prefers tea, just that she would prefer tea in this particular instance.

Here's an example conversation:

Tom: Let's go out to Paddy's Pub tomorrow.

Andrew: We should invite Beatrice too.

Simon: Doesn't she prefer wine? Paddy's wine selection is very overpriced.

Andrew: Yeah, but she likes chocolate stouts almost as much. She would probably prefer to get chocolate stout rather than overpay for bad wine.

As stated, Beatrice in general prefers wine, but specific to this scenario she would rather have an chocolate stout.

This depends on what city or town you're talking about. Since you mention the US in your question, I'm going to answer from that point of view.

Manhattan, a part of New York City, famously has all three. According to NYCSubwayGuide, Uptown is the northern part (anything north of 59th Street), Downtown is the southern part (anything south of 14th Street), and Midtown is the part in between (between 59th Street and 14th Street). This is from the tradition in the northern hemisphere of referring to the cardinal direction north as "up" and south as "down". Additionally,

While Uptown, Midtown, and Downtown are geographic regions of Manhattan, the words uptown and downtown can also mean your direction of travel. If you head north or towards the Bronx or Queens, you can say you are headed "uptown"; if you head south or towards Brooklyn, you can say you are headed "downtown."

However, many towns only have a "downtown", which is basically the business district of the town and generally doesn't have anything to do with the cardinal directions (traditionally, such districts are centrally located). In fact, Cambridge Dictionary's American definition of downtown specifically references the "central part of a city". This is the most common meaning of downtown in the US.

On the other hand, the town where I live now only has an "Uptown". The town is built on a hill; our central business district is called "Uptown" instead of "downtown" because it runs along the ridge of the hill, so you must literally go up to get to Uptown from almost any other part of the town. Thus, when you say "I'm headed uptown" here you may be going either north or south, unlike in Manhattan. Another example of this is Charlotte, North Carolina, which also calls its "downtown" "Uptown" for similar historical reasons (and because they think it sounds cooler).

Unfortunately, this means that the only way to know for sure what is meant by one of these terms for a particular city or town is to look it up or ask a local. However, in most cases "downtown" will mean the city's main business district, wherever that happens to be.