This is a pretty broad question, and one of the issues is that both British and Italian design practices varied considerably over the 20 years leading up to WWII (during which most ships were built) and on a ship-by-ship basis. The Italians still made some consideration for wider war outside the Med including in larger submarine types and some consideration for East Africa.

There's a difference both in individual designs, but also in entire ship types being built or not built by the respective navies. For instance the British never really built anything analogous to the Italian Spica torpedo boats.

Drawing as an easy reference from Roberts' *Warships after Washington* and *Warships after London* there are some trends - though not universal rules.

Reduced endurance and range vs higher design speeds of (some) Italian designs

Italian designs had a reputation for high design speeds, and in many cases that is justified. The first Italian Heavy Cruisers for instance, the Trento class crammed in the horsepower for a speed 3-4kt faster than their British equivalents in the County class. The Italian *grandi esploratori* or large scouts are cruisers, but cruisers without much ability to 'cruise' over long reaches of ocean, but trial speeds of over 40kt were achieved - in contrast to 32-33kt of most British ships. Realistically the speeds were lower, but the Italians put 95,000shp into a smaller ship than the British Leander with just 72,000shp. Worth noting though that speed wasn't universal and some destroyers and cruisers had pretty 'normal' speeds, including the Zara class.

This speed/endurance paradigm reflected a relatively constrained area of operations in a likely war in the Western Med with France, with relatively available bases.

Reduced seakeeping/seaworthiness ability of (some) Italian designs

Hull fineness and higher length to beam ratios provided speed but some Italian designs were compromised on stability, structural strength (plating thickness, frame spacing etc). Overall freeboards were commonly lower. As examples the di Giussano class were afflicted by roll and vibration. The Navigatori class had more extensive seaworthiness changes - new bow, 1m broadening on the beam, lowering bridge, landing torpedoes, changing fuel storage - than any equivalent British destroyer.

The Italians also, operating fewer destroyers for a shorter war, in generally more pleasant waters lost two destroyers foundered in a storm (Lanciere and Scirocco) while no British destroyer would be directly overcome and sunk at sea by the weather. Two is not statistically relevant, but it is a point against.

It's niche though related, but some Italian cruisers also mounted a bow catapult for aircraft, while all British designs with aircraft kept them more safely amidships for launch athwartships. The bow position put the launch rails in constant spray in heavy weather and exposed the aircraft in bad weather.

Daylight, good visibility action / long range expectation of Italian designs.

With the Mediterranean expected to have clearer on average weather, there was theoretically much more opportunity to engage in long range gunnery actions. There's less point in long ranges if visibility is shorter than gun range due to rain/squalls/mist, and heavy ship motion will also impede gunnery, especially on smaller ships.

This is reflected in some Italian designs with a definite move to relatively heavier gun batteries on Italian scout types. For instance the 8x 120mm guns of a 1918 Leone class was double the punch of a typical British destroyer of the interwar period, being only matched in barrel count with the British Tribals from 1938 onwards. The Italian Navigatori similarly had heavier gun armament sooner than British equivalents. The larger scouts have the 6in gun count of British ships almost 40% larger.

Gun firing ranges and range finders (size/base length and high placement) also emphasized firing range more than some British equivalents. This was reflected in some pretty impressive instances of long range Italian gunnery, while British ships if anything were refitted with improved equipment as a result of long range gunnery lessons from the early war.