Preocupar vs. inquietar

The Spanish words 'preocupar' and 'inquietar' both translate to 'to worry' or 'to concern' in English, deriving from the feeling of unease about a potentially adverse situation. However, their usage in the language slightly differs based on context and intensity.

Preocupar

This word is used when someone is worried or anxious. The concern here is generally greater and often deals with specific problems that one anticipates.
Me preocupa que no llegues a tiempo para el examen.
(I am worried that you will not arrive in time for the test.)
La falta de empleo es una situación que preocupa a muchas personas.
(Unemployment is a situation that worries many people.)
Su salud me preocupa.
(I'm worried about his health.)

Inquietar

'Inquietar' also means to worry or concern, but is often used to denote a lesser degree of worry, usually preceding a full state of worry or concerning something less direct or less immediate.
Le inquieta la idea de viajar solo a un país extranjero.
(The idea of travelling alone to a foreign country makes him uneasy.)
Su comportamiento extraño me inquieta.
(His strange behavior unsettles me.)
Inquietan las noticias sobre el cambio climático.
(The news about climate change are unsettling.)

Summary

'Preocupar' and 'inquietar' are both Spanish verbs related to anxiety or concern. However, 'preocupar' often denotes a more substantial degree of worry pertaining to specific situations while 'inquietar' reflects an uneasiness or mild disturbance about something usually less immediate or direct. Therefore, the usage of each depends on the situation at hand.