No, circa vuol dire più o meno (more or less, approximately) almost significa che manca qualcosa per arrivare a ... for example in my country there are about 2000 inhabitants It might more or less 2000 if i tell in my country there are almost 2000 inhabitants, significa che sono meno di 2000 abitanti, it means there are less of 2000 inhabitants

/circa/ significa /about/ or /approximately/. /quasi/ significa /almost/. Their usage follows from the meaning, we stick to it.