A big difference being that, unlike Italy, Britain wasn't ruled by a murderous, Fascist Dictator when it ruled Somalia.
When Italy invaded British Somaliland Mussolini was their leader (Churchill was ours). Although the British then managed to drive the Italians out thanks to a massive sea invasion.
Actually, it had nothing to do with relieving Italian Somaliland of the Mussolini dictatorship. It was an opportunity to increase British possessions that was seized while Italy was diverted elsewhere. The Italian Somaliland had become a wealthy paradise compared to the British Somaliland because so many immensely wealthy Italians had set up home there, and it was therefore quite a desirable plot of land. This division in wealth between the north and south is partly to blame for the ensuing civil wars.