The words 'desire' and 'motivation' often appear in different kind of sentences for (what I assume is) grammatical reasons, but I have a really hard time separating them as concepts.
When we talk about desire or motivation it seems like we ultimately are talking about why we act; we are seeking some kind of explanation of our actions and without desire or motivation there will be no action. We act because we desire/are motivated by X…. What motivated you / what desires caused you to do that? Do you desire x / are you motivated by x?
It can be a physical (causal) explanation, e.g. the increase in dopamine drove me, it can be a design explanation, e.g. humans are 'designed to' pursue sugar, fat, sex etc, or it can be an intentional explanation, e.g. I work hard because I want money.
It might feel like an explanation is sometimes about desire and sometimes about motivation but are we really talking about any conceptual difference?
Please help me sort this out.
A side point (about MY definition of a value)
I understand that we can value something without being motivated by it. But a value to me is just a type of belief i.e. a belief about what we desire or should desire. Hopefully our values correspond to our desires; our values can influence our desires over time, but believing we value something does not automatically make us act accordingly; we have to make it emotional if we want something to drive us to action i.e. if we want something to motivate us / be a desire.
Wordnet says that desire is "the feeling that accompanies an unsatisfied state" or "an inclination to want things". The first definition I would say describes a force of motivation i.e. the two words refer to the same phenomenon (the feeling which causes the action), the second definition describe a phenomenon which is either a force for motivation or what I referred to as a value.
Best Answer
Your desires are things you want, while motivation is your reason for performing a given action. You can be motivated by your desires ("I want to buy a new car, so I should save some money!"). Here, your desire is "a new car", and the action you take is "save some money". Your motivation for saving money is your desire to buy a new car. Technically, almost everything you do could be said to be motivated by desire ("I don't want to starve to death, so I should eat a sandwich"), but I wouldn't say they're the same thing. Just because someone wants something to happen doesn't mean their actions will reflect that.