There were some like these:
I just put all of them into the same pile, counted them together and referred to all of them as Hemd. I had learned in school that paita = das Hemd, and in Finnish all these are different types of paitas, especially in the colloquial language. From the top: neulepaita (knitted shirt), paita (shirt), T-paita (T-shirt) and... I guess another paita. We do have a separate colloquial word for a hoodie (huppari), but nobody would be surprised if you said "I'll put my paita on" and then put your hoodie on. Basically the same thing as when you "go out for a coffee" but drink tea instead. Similarly, paita is often used in the broad sense of an upper body garment (except a bikini top, which is definitely not paita). The most typical paita would be a thin, long-sleeve cotton shirt without buttons:
But it turns out, Hemd only means a specific kind of paita, namely this (in Finnish kauluspaita):
And the other paitas are Pullover, Jäckchen, T-Shirt, and so on. We eventually de-confused the discussion and ended up making more than one pile of baby paitas - still probably less than a German would, because I said I'm not able to tell the difference between some types of garments because they're both paita to me.
If a Finnish novel is translated into German, and the main character puts a paita on, it should be translated differently based on what kind of person he is. Maybe he puts a Hemd on if it fits his character, but it can also be something else. A good human translator would be able to pick an appropriate word, but I can imagine this problem is very difficult for machine translation! Using the wrong word would make the atmosphere all wrong, for example if a rascal puts a button-down shirt on and goes out, the German reader would be left wondering why he's suddenly dressing up so formally.
In a similar vein, I recently read a column about the differences of being successful and being successful. Namely, there are two words for "to succeed" in Finnish, onnistua and menestyä. Onnistua (in this context) means more like "to produce something of good quality" and menestyä more like "to produce something popular" or "to rank highly compared to others". Similarly, there are two words which roughly translate to successful, onnistunut (something which has high quality) and menestynyt (something which has gained popularity). The column was about how we should strive to "onnistua" and not "menestyä", that is, we should focus on quality and not popularity / winning. It went on to list examples, like, an athlete should strive to onnistua (perform as well as he can) instead of menestyä (it might be possible to win even if you under-perform if the others are even worse, and it's also tempting to cheat in order to win, whereas cheating won't help you to onnistua). And at work, we should also try to onnistua (do our job well) instead of menestyä (achieve a high position).
I hope nobody needs to translate that column into English! In many contexts onnistua and menestyä would be translated into "to succeed" / "to achieve" / "to accomplish", but I don't think these English words are able to express the difference the column focuses on.
"To achieve" is defined as "successfully bring about or reach (a desired objective or result) by effort, skill, or courage" or "to succeed in something" or "to become successful, to reach a goal".
And "to succeed" is defined as "to happen or terminate according to desire / have the desired result or to accomplish what is attempted or intended".
The dictionary definition of "to succeed" matches "onnistua" better, but if we say "she has been successful in her career", we'd use it in the sense of menestyä. We can also say "she has achieved a high position" to mean the same thing. To say that somebody wrote a book of good quality (which was not necessarily popular), I wouldn't use any of these words, I'd just say "she wrote a great book". "She wrote a successful book" would mean the book was popular. It would be weird to say "the movie was a success" to mean that it was a great movie although it didn't sell well.
(But anyway, as in all kitchen linguistics episodes, this is just my view on these words as a non-native English speaker, and I'm welcoming further insights into what these words mean and enlightening example usages.)
(A note to Germans, successful is spelled with one L. It can be also thought of something full of success but that's how it's spelled anyway. It's one of the most common misspellings I see in when I read English texts written by Germans.)