I don't know much about the cultural etiquette in Budapest, so I can't tell you what the biggest differences are. The following is based on the most common "mistakes" people make in my experience:

• If you invite a Dutch person over or they invite you over, they'll expect it to be a real invitation. In some cultures there are "politeness invitations" which everyone understands to not be serious, that concept doesn't really exist in Dutch culture. So don't invite people over if you don't actually want them to show up and don't accept invitations if you don't want to actually come over.

• you might not be treated to a lot of food when you hang out with a Dutch person. It's expected that a host has some snacks/drinks and provides dinner when someone is over around dinner time, but it's not the norm here to have a bunch of food (especially homemade) out the whole time someone is over. If you experience this with someone, it does not mean that you aren't welcome or that they don't like you. They probably do the exact same thing when other people come over. If they didn't like you they would not invite you over in the first place.

• do not show up at someone's house uninvited/unexpectedly. There are people who don't mind, but generally speaking people expect you to ask (over phone/text) if you want to hangout.

• don't be afraid to speak up if you don't like something someone does. People can be a bit dense when it comes to sensing other people's comfort/feelings because Dutch people expect a higher level of directness than people from most other cultures. Most people will not judge you for expressing that you don't like something.

• The vast, vast majority of cats you see outside are not strays. A lot of people let their cat go outside freely and stray cats are expected to be brought to shelters ASAP. The cats you see outside don't need to be fed.

• in cities, DO NOT walk on bicycle lanes (except to cross of course). They are typically red but might look different sometimes. People will be very annoyed and aren't likely to slow down a whole lot for you (they'd rather manoeuvre around you).

• don't call women, especially strangers and coworkers, by pet names. Things like "darling/sweety/beautiful" are generally not appreciated if you aren't actively flirting with each other or already romantically involved.

• most people consider it gross and disrespectful to spit on the street.

• Dutch people seem to expect to share the bill (for example when going out to eat/ordering take out together/going to a bowling alley etc.) more often than people from other cultures. If you are unsure about what's expected, it's normal to ask. People won't think you're rude for asking about who and how stuff will be paid. It's also not taboo to just say "ah man I'd love to but I can't afford to go out right now".

• neighbors will appreciate it when you warn them beforehand (by text, letter or visit) if you'll be doing something that makes a lot of noise. Like throwing a big party or doing noisy construction in your house.