Two verbs, two intensities
Spanish has two common verbs that can both be translated "to love": querer (whose core meaning is closer to "to want" or "to care for") and amar (a more elevated, specifically love-focused verb). Te quiero and te amo ("I love/want you" and "I love you," respectively) pull from those two verbs, and their emotional force can differ in context. The RAE also defines querer as amar, so the meanings overlap.
Te quiero: the everyday version
Na’atik’s teaching guide presents te quiero as an everyday expression of affection across relationships: friends tell each other te quiero, family members say it routinely, and romantic partners use it too, especially outside of the most serious or formal declarations. Although querer also means "to want," that dictionary sense does not explain the emotional force of every te quiero. In this teaching distinction, it expresses care and affection without necessarily being a solemn declaration. The noun for that affection, cariño, has "darling" as only one of the five senses RAE lists for it.
If you're unsure which to use with a new romantic partner, te quiero is often a useful everyday option, but its force still depends on the relationship.
Te amo: saved for something bigger
Na’atik describes te amo as an intense expression of love: the kind of statement that typically comes after a relationship has had real time to develop, not something said casually or early on. Using it too soon in a new romance can read as unexpectedly intense or even a little theatrical to a native speaker, roughly the way declaring "I am deeply, permanently in love with you" would land oddly if said to someone you'd been dating for two weeks.
Romantic intensity isn't the only place te amo shows up, though: Na’atik also gives parents and children as a setting for it, expressing strong family affection rather than romance. That example is a reason to check the relationship rather than assume the phrase must be romantic.
A regional wrinkle worth knowing
Regional and personal habits affect how these phrases sound. The Na’atik guide offers an everyday-affection versus intense-love distinction; it does not establish a single Spain-versus-Latin-America rule. A couple may use te quiero for serious love, and te amo can express family affection.
For a warm, clearly non-romantic alternative (telling a friend you value them without touching either "love" verb), Spanish speakers often reach for me caes muy bien ("I like you a lot," literally closer to "you strike me very well") instead.
A third rung below both: "me gustas"
There's a lighter step below even te quiero for early romantic interest: me gustas ("I like you," in the sense of "I'm into you," not the plain-liking sense of me gusta for a food or a movie). It signals attraction without committing to anything like love, closer to a crush confession than a relationship milestone. It's often what gets said before either te quiero or te amo is even on the table.
Put in order of escalating commitment, the three sit roughly as me gustas (attraction, no commitment implied) → te quiero (affection, appropriate for friends, family, and established but not necessarily deeply serious romance) → te amo (deep, committed romantic love). This is a rough learning aid: me gustas expresses attraction, while the two love expressions overlap and depend on context.