Explosión vs. estallido
While both words describe violent releases of energy, explosión focuses on the expansive force, fire, and destruction, whereas estallido emphasizes the sudden crash, shattering action, or the deafening sound produced by the event.
Explosión
B1This is the standard, most common term for the chemical or physical release of energy. It focuses on the destructive mechanics: the shockwave, the heat, and the outward expansion of force. When discussing a bomb, this word highlights the damage and the event itself.
La explosión fue tan fuerte que destruyó el puente.
(The explosion was so strong that it destroyed the bridge.)
Los bomberos evacuaron la zona por miedo a una segunda explosión.
(The firefighters evacuated the area for fear of a second explosion.)
La onda expansiva de la explosión rompió las ventanas a tres calles de distancia.
(The explosion's shockwave broke windows three streets away.)
Nadie resultó herido en la explosión del coche bomba.
(No one was injured in the car bomb explosion.)
Estallido
B2Derived from the verb estallar (to burst/to pop), this word focuses on the auditory experience (the bang or crack) or the sudden act of shattering. Regarding a bomb, it describes the deafening noise or the moment the casing bursts apart.
El estallido de la granada nos dejó sordos momentáneamente.
(The blast of the grenade left us momentarily deaf.)
Se escuchó un fuerte estallido y luego se fue la luz.
(A loud bang was heard and then the power went out.)
El estallido de los vidrios causó más pánico que el fuego mismo.
(The shattering of the glass caused more panic than the fire itself.)
Confundieron el estallido de un neumático con un disparo.
(They mistook the popping of a tire for a gunshot.)
Summary
Use explosión when you are referring to the general event, the scientific reaction, or the resulting destruction. Use estallido when you want to emphasize the sudden noise, the bang, or the specific moment something bursts or shatters.