In English, 'pasta' is not usually a plural noun, it is a mass noun (or 'uncountable' noun). Arguably, you could refer to different kinds of pasta as "pastas" (although most English speakers would not), but if referring to pasta as one substance it is just "pasta".
The advert you are referring to is not saying that different kinds of pasta are the same - they are clearly not. Farfalle, penne, spaghetti, are all different in shape if nothing else.
The advert is clearly talking about the quality of pasta as a substance, saying that not all brands of pasta are the same, and suggesting that the one being advertised is superior.
Note that this applies to English and may well be different from some Latin languages - the term 'spaghetti', for example, is a Latin plural form (just as 'cacti' is the plural of cactus) and technically one single strand of spaghetti should be known as a 'spaghetto'; however, this is unknown to the majority of native English speakers and we just don't use that term. Additionally, don't take this as a rule for all Latin languages - for example, neither Italian nor French uses 'cacti' as the plural for cactus.