When I first went to Mexico, I was surprised to find that they didn't have lemons, only limes. However, they used both the word limón and lima, to refer to big limes and little key limes respectively. I thought it was kind of weird.
When I went to Brazil, I was curious to find out what they called these fruits. It turns out they only have one word: limão, which mostly just refers to limes, though they knew what a lemon was--a limão forte (strong), a yellow fruit too sour to eat.
In Spain, it was limes that didn't seem to exist, just yellow limónes. I've always thought the whole thing weird, so of course I had to ask when I got to Ecuador.
Here, they only really eat limes, and call them limónes. But the yellow fruit that's really sour? It's a LIMA, completely backwards of English! Why is this so complicated? Nobody seems to confuse naranjas (oranges) and toranjas (grapefruit.) It's baffling!