The 3 "passion" is vanity. In some way in their early development, the 3 received a message about reality that basically said "there is not enough love/attention to go around in the world", and so the person seeks to be/appear very valuable to get their piece of the love pie. This is why they are a heart/image type. Their passion is vanity because they identify with their idealized self & need to be seen that way by others.
They tend to try & fill up their love void through achievements, recognition, & success in whatever areas they find significant. They likely internalized external values at a young age, noting what caused people to be admired & given attention, and they likely also build their image around whatever particular strengths they have that received acknowledgement also. They identify with this positive self-image, and they "market" it to others. When they fall short of it is when their vanity leads to deceit - they so badly need to feel & be seen as their idealized self, a self that is valuable to others, that they may go into denial about their shortcomings & exaggerate certain things about themselves unwittingly. Their vanity prevents them from admitting their failures & flaws, even to themselves, and they'll go to lengths to hide it. This creates a viscous cycle because they tend to end up the type of people who never feel loved for who they really are & maybe people who have spent their life pursuing things that didn't really fulfill them personally.
The 5 passion is avarice. In some way in their early development, the 5 received a message about reality that basically said "the world requires/takes a lot & gives back very little", and so the person seeks to accumulate & hoard their mental, emotional & physical energy in fear of external things sucking them dry & giving them nothing back. This is why they are in the head/fear triad. In order to conserve their energy, they tend to demotivate themselves by not feeling, because of course if nothing affects you emotionally then you are not particularly motivated to act. The person makes very little matter to them so there is little to lose & little to maintain. Because head knowledge is hard to lose & relatively easy to gather (not so much emotional/physical energy), they make seek this to feel more "equipped" to deal with the demands of life.
But the get caught up in a cycle of not seeking pragmatic knowledge. They tend to want to unravel the grand mysteries of life, perhaps, because then they may be able to know how to navigate it efficiently. The idea is to store up all this info until one day they are finally ready to join the world, but of course, they never really feel ready & small things drain them too easily. In order to justify this avarice, they have to be detached. They cannot really care that they contribute little & achieve little & connect with few or no people. They will intellectualize feelings in order to dismiss them so as not to act on them. If they don't care, then they have no reason to "share", to make effort & use their time/energy/money towards anyone else. They keep obligations & desires minimal as well, so as to expend less of themselves. This creates a vicious cycle because if they never make any effort to gain anything (because they expect the contribution involved to not be worth it), then they continue to have little & this feeds their fear. However, they may sometimes share some of their acquired knowledge as a way of "giving", because they don't want to give in ways that involve emotion or physical energy so much.
As you see, the fixations & passions are quite different. I'd try to determine whether vanity/deceit or avarice/detachment is the core issue in how you're motivated or inclined to navigate life.
I wrote this concerning 3 vs 5 for 4 wings, but it makes some distinctions for the types themselves:
I think a big indicator is motivation….5s tend to kill it & 3s adopt it.
Naranjo mentions "feelinglessness" and "negativism" among other defenses 5s use to not act, so as to justify the greed of their own energy/time/thoughts. They essentially devalue their own feelings & emotions by turning them into "shoulds" or obligations from outside, instead of wants & needs from within. By doing this, they don't have to act & face their fear of "not enough" in themselves & the world. However, this emptiness perpetuates a sense of "not having enough" & justifies withholding.
3s do something sort of similar, but in reverse. To avoid their sense of worthlessness, they take on "shoulds" and obligations from outside as personal values, wants & needs. They deceive themselves, then, as to who they are & what they really want as individuals. In achieving things, they bury worthlessness under a heap of success that has little to do with what is personally fulfilling for them as an individual. Thus, they are motivated to act, to avoid worthlessness & the emptiness of their success. They can't acknowledge & develop their personal values without confronting whether they actually have any value themselves, because that has to be validated first. There can be a kind of numbness from avoiding the emotions needed to form personal values, and this too is avoided with action.