brüllen
to yell
To shout, call out, or cry very loudly. Usually refers to people.
Hör auf zu brüllen, ich stehe doch direkt neben dir!
Stop yelling, I'm standing right next to you!

to roar / yell
Loading your saved state.
to yell
To shout, call out, or cry very loudly. Usually refers to people.
Hör auf zu brüllen, ich stehe doch direkt neben dir!
Stop yelling, I'm standing right next to you!

The meaning of 'brüllen' (to roar/yell) depends heavily on context. Is it an animal (lion), an angry person, or a laughing person? The situation makes it clear whether it is roaring/yelling out of anger, pain, or joy.
Als der Löwe brüllte, hielten sich alle Kinder die Ohren zu.
When the lion roared, all the children covered their ears.
When people 'brüllen' (yell), the reason is often expressed with the preposition 'vor' and an emotion in the dative. Typical combinations are 'vor Wut brüllen' (to yell with anger) or 'vor Schmerz brüllen' (to scream with pain).
Als er den Kratzer am Auto sah, brüllte er vor Wut.
When he saw the scratch on the car, he yelled with anger.
In connection with large, powerful animals such as lions, tigers, or bears, 'brüllen' means their typical loud call. In this case, the subject of the sentence is almost always an animal.
Man konnte die Tiger im Nachbargehege brüllen hören.
You could hear the tigers roaring in the neighboring enclosure.
In colloquial language, 'brüllen' can also mean 'sehr laut lachen' (to laugh very loudly). This use is informal and often part of the expression 'vor Lachen brüllen' (to roar with laughter).
Die Komödie war so lustig, das ganze Kino hat gebrüllt.
The comedy was so funny, the whole cinema was roaring with laughter.
to laugh
'lachen' and 'brüllen' can both describe someone laughing for fun. 'lachen' is the normal and neutral word. It only says that someone is showing joy or amusement. In this context, 'brüllen' means very loud, uncontrolled laughter and sounds colloquial. Learners may confuse the words because people sometimes say: 'Er brüllt vor Lachen' (he is roaring with laughter). Without this context, however, 'brüllen' often means to yell or call out loudly. For normal laughter, 'lachen' is the safe choice.

Bei dem Witz hat die ganze Gruppe vor Lachen gebrüllt.
The whole group roared with laughter at the joke.
Meine Mutter lachte, als sie die alte Familiengeschichte hörte.
My mother laughed when she heard the old family story.