General quantities with "alle"
When you want to talk about "all" of something in a general sense, Dutch uses the word alle. You place it directly in front of a plural noun or an uncountable noun, without any article.
| All donations are for the charity. | Alle donaties zijn voor het goede doel. |
| All volunteers work hard in the winter. | Alle vrijwilligers werken hard in de winter. |
This translates simply to "all donations" or "all volunteers" in general, rather than a specific batch that you are pointing out.
Specific quantities with "al de" and "al het"
When you refer to a specific, defined group of things—meaning "all the" or "all of the"—you use the word al followed by the definite article (de or het).
Use al het for het-words:
| All the food goes to the foundation. | Al het voedsel gaat naar de stichting. |
Use al de for de-words (both singular and plural):
| All the clothing is for the poor people. | Al de kleding is voor de arme mensen. |
| All the coats are for the charity. | Al de jassen zijn voor het goede doel. |
Spotting the difference
The key difference is just between general statements and specific ones. You will often see both forms used together when discussing charity campaigns, distinguishing between general goodwill and tracking specific proceeds.
| All donations are welcome, but all the proceeds go to the orphanage. | Alle donaties zijn welkom, maar al de opbrengst gaat naar het weeshuis. |