Haut-parleur vs. enceinte
The French words haut-parleur and enceinte both translate to "speaker" in English, but they refer to different types of devices or components. A haut-parleur is the actual electronic component that produces sound, a public address system, or the speakerphone function on a phone. An enceinte is the physical cabinet or standalone box unit that houses one or more of these sound-producing components, such as a Bluetooth or stereo speaker.
Haut-parleur
A haut-parleur refers strictly to the internal driver or sound-producing cone itself, the speakerphone mode on a mobile telephone, or a public address speaker like those used in train stations or megaphones.
Mets ton téléphone sur haut-parleur pour que je puisse l'entendre.
(Put your phone on speakerphone so I can hear him.)
Le haut-parleur de la gare a annoncé le retard du train.
(The station speaker announced the train's delay.)
Il faut remplacer le haut-parleur gauche de la voiture.
(The left speaker of the car needs to be replaced.)
La membrane du haut-parleur est déchirée et le son grésille.
(The speaker cone is torn and the sound is crackling.)
Le maire a parlé dans un haut-parleur lors de la manifestation.
(The mayor spoke into a megaphone during the protest.)
Enceinte
An enceinte refers to the complete speaker enclosure, cabinet, or standalone unit that you buy as a consumer product, such as a portable Bluetooth speaker, a smart speaker, or the large wooden boxes in a home theater system.
J'ai acheté une nouvelle enceinte Bluetooth pour les vacances.
(I bought a new Bluetooth speaker for the holidays.)
Les enceintes de son home cinéma sont très puissantes.
(The speakers of his home theater are very powerful.)
Cette enceinte intelligente peut contrôler les lumières de la maison.
(This smart speaker can control the lights in the house.)
Il a construit une enceinte en bois pour améliorer l'acoustique de son salon.
(He built a wooden speaker cabinet to improve the acoustics of his living room.)
N'oublie pas de recharger l'enceinte avant la fête ce soir.
(Do not forget to charge the speaker before the party tonight.)
Summary
In short, use haut-parleur when talking about the raw sound-producing component, a public announcement system, or a phone's speakerphone function. Use enceinte when referring to a standalone, enclosed speaker unit like a Bluetooth speaker, a smart speaker, or stereo equipment.