If you mean the difference between the two L’s in the word little, the first one
[l] is the same as the Italian L of your acquaintance and is sometimes called a “bright L” or a “clear L”, while the second is an allophone of English sometimes referred to as a “dark L”, written
The key difference is that the dark version is velarized, which here means that the back of your tongue flattens out and moves up a bit. The normal demo-word for this sound is FULL. If you have ever heard Catalan spoken, you will find that the Catalans often have dark L’s where a Castilian speaker would have a bright one like you do. It probably sounds a bit “swallowed” to your ear.
The exact distribution of these two allophones for phonemic
/l/ varies by region, speaker, and syllable position. Some speakers have only one or the other of the two, while others have both. [reference]
Technically speaking, the dark L is:
The velarized alveolar lateral approximant, also known as dark l, is a type of consonantal sound used in some spoken languages. The regular symbol in the International Phonetic Alphabet that represents this sound is ⟨lˠ⟩, though the dedicated letter ⟨ɫ⟩ is perhaps more common.
In contrast, the other L is:
The alveolar lateral approximant, also known as clear l, is a type of consonantal sound used in some spoken languages. The symbol in the International Phonetic Alphabet that represents dental, alveolar, and postalveolar lateral approximants is ⟨l⟩, and the equivalent X-SAMPA symbol is l.