eSIM or roaming: which is really better value abroad?
In short: outside the European Union a travel eSIM is almost always cheaper than the roaming of your Italian operator, because you pay in advance only for the data you need. Inside the EU roaming is already included ("Roam Like at Home"), so an eSIM is mainly worth it as a backup or to get past the fair use limit.
Inside the EU: roaming is included
If you travel to Spain, Greece, France, Croatia or Portugal, your Italian plan works as at home at no extra cost. An eSIM is not essential here: it can serve as a backup network, give you a predictable cost, or cover you if you use more data than the roaming limit allows.
Outside the EU: this is where an eSIM makes the difference
In non-EU countries pay-as-you-go roaming gets expensive. Iliad, for example, offers no package for countries such as Egypt and applies high pay-as-you-go rates; Vodafone's "Travel" packages start from about €19.99 for a few days. With an eSIM of a few GB you usually spend much less for the same trip, and you know in advance what you pay.
How to use the eSIM and avoid roaming
Install the eSIM before you leave, turn off data roaming on your Italian SIM and set the eSIM as your data line. Your number stays reachable for calls, SMS and apps such as WhatsApp, while you browse on the local network at a fixed price.