Hi there!
Quite complex subject, actually not complex "extensive" is a better adjective...
Well, firstly I suggest searching old post at English Expert, below we have one of those sources of excellent matterial found here:
https://www.englishexperts.com.br/forum/infinitivo-x-gerundio-quando-e-como-usar-o-ing-t10819.htmlI will try to help a little bit, right!
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ING is mostly found in Verb tenses, the so called "
continuous tenses" (nowadays "
progressive tenses");
Verbs at the beginning of a sentence;
Nouns, very common structure, for example: Human
beings,
beginning,
belonging, so on...;
Adjectives, lots of ajectives are formed using "ING" and that seems to be part of your question...
This movie is boring. O filme é chato.
She is captivating. Ela é cativante.
They are amazing. Eles são surpreendentes.
You are annoying. Você é irritante.
See, when we use an "ing" adjective we're referring to "something that causes - boredom, irritation, annoyance...
If you are
bored (1-entediado) you' re not necessarily
boring (2-um chato). In this sentence we have two different adjectives 1-how one feels, 2-what one causes or how something/he/she makes you feel.
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Nos seus exemplos temos:
Small change - como o PPAULO esclareceu, comumente é "troco, dinheiro trocado" é substantivo;
Small changing "pad" - small changing é adjetivo, qualifica o que vem depois (pad was my own contribution

) são aquelas mesinhas pra trocar o bebê.
Cheers!