Do you mean 'latterly' and 'lately'? As an adverb of time, there is no difference in meaning: they both have a similar meaning to 'recently'. 'Latterly' is a relatively unusual adverb: it is quite formal and literary. If I were you, I'd keep it in your passive vocabulary, as something that you understand but don't necessarily use. I think it would sound a little odd if a young person learning English were to use the word 'latterly'. My advice would be to use 'lately' or 'recently' instead.

I think that both latterly and lately are synonymous. They both mean recently, or within a short period of time before now. Lately is more commonly used than latterly. I do use latterly occasionally, more often in writing. It does sound a bit more old fashioned and formal though.

I think the word that you want is "lately." Las dos palabras que escribiste no existen.