The key difference is that by June 1944, Italy was effectively no longer a sovereign state allied with Germany, but effectively under German occupation.

After the Allied invasion of Sicily in July 1943, members of the higher echelons of the Italian government conspired with King Vittorio Emanuele III to remove Mussolini from power and negotiate and armistice. On July 24, 1943, the Grand Council of Fascism (effectively the cabinet) passed a no confidence vote and the king dismissed Mussolini from the position of Prime Minister, and Mussolini was arrested and imprisoned the next day.

Italian generals meanwhile were in Lisbon, Portugal negotiating an armistice with the Allies, which was publicly announced on Sept. 8. When the armistice went into effect, the German Wehrmacht had moved eight divisions into Italy and countered with Operation Alaric, under which they attacked and disarmed the Italian military. Tens of thousands of Italians were killed and some 700,000 Italian servicemembers were rounded up and placed in POW camps. The Italian navy set sail for North Africa and was attacked by the Luftwaffe, with the battleship Roma sunk with heavy loss of life.

Rome itself was the scene of heavy fighting, as Italian military forces and carabinieri attempted to hold off German paratroopers from seizing the city. The royal family managed to escape to Allied-held Brindisi, but Allied forces were unable to enter the city (there was a plan for the 82nd Airborne to land in the city, but airfields were in German hands). German forces gained control of the capital after fierce fighting, after which Italian units surrendered and were disarmed.

In the meantime, Mussolini was freed from prison by German forces on Sept 12, and a couple weeks later was installed as head of a new Italian Social Republic (RSI), which was the puppet regime nominally in charge of German-occupied Italy (parts of which were directly annexed to Germany).

From this point on, a parallel Italian civil war was fought between the RSI and anti-fascist forces, which consisted of an Italian Co-Belligerent Army fighting with the Allies in their Italian campaign, and a large collection of partisan groups (ranging the political spectrum from Christian Democrats to socialists and notably the Italian Communist Party) fighting the RSI behind the frontlines. A number of major partisan uprisings would occur in the summer of 1944 and the spring of 1945, the latter of which occurred at the very end of the war and saw Mussolini's capture and death at partisan hands.

When Allies liberated Rome in 1944, the massive public demonstrations were by a city populace that were celebrating the end of a German military occupation that had been bloodily imposed on the city and that signaled the end of the bloody civil conflict that would continue in other parts of the country well into the following year.