Okay, I see where the confusion lies: fanservice is what that T&A in most anime is called. Ecchi is when that’s the main focus of the show. Again, it’s like how in a PG-13 movie they’re allowed a certain level of “suggestive themes” like an implied sex scene, but if they’re too blatant/obvious/frequent they’ve got to go up to an R rating.

So, like,

• Yoruichi in BLEACH: fanservice
• a zombie anime where every girl’s chest is as big as their heads and the shirts cling impossibly close to their skin and bullets travel between their individually flapping breasts (Highschool of the Dead): ecchi
• naked wolf girl with no visible tits in an otherwise grounded story about Medieval commerce (Spice & Wolf): fanservice
• an entire anime based around gaining superpowers by drinking breast milk straight from the tap (Qwaser of Stigmata): Ecchi
• beach or onsen episodes: fanservice
• harem anime where the girls are constantly in states of undress: ecchi

The anime community (especially in the West) has had a bad reputation about making the fanservice front-and-center (for various reasons I won’t get into here) but I think one should make a clear separation between what you see at fan meetups and what the actual content of the anime is.