There are several key differences between the fall of France and the fall of Greece which explain the comparative lengths of each campaign.

The first and perhaps most important difference were the combatants involved. In the French case it was the well equipped, well trained and professional Wehrmacht who would undertake the brunt of the combat. The German army was extremely formidable and had a high level of morale compared to the French army which had suffered from years of underfunding in the aftermath of the Great War. By contrast, it was the Italian army which initially invaded Greece; the Italians were much less well equipped than the Wehrmacht and suffered from poor morale and much poorer leadership than the German army in the French campaign. A perfect example of this is that out of thousands of motorised vehicles promised to the Italian forces, only 107 were delivered to Italian troops in Albania by the start of the campaign. Their combat performance was much poorer against the Greeks than the German performance against the French.

The second is simply a matter of natural geography. Greece is naturally mountainous, especially on the Albanian-Greek border which was initially the main point of attack. This made it extremely difficult to move large numbers of troops and equipment quickly to the front as well as to keep them well supplied. France too was protected by natural borders, most notably the Ardennes forest, but the key difference was that the Allies mistakenly believed that the terrain was impassable for the German Panzers and as such left the area poorly defended. This allowed the Germans to smash through these defences and encircle the majority of the Allied troops in Belgium and northern France very quickly. The Greeks knew the value of their terrain, where was passable and where wasn't, and were very effective in using it which significantly delayed the Italian offensive.

Further to this, whereas the German attacks through the Ardennes were a complete surprise to the Allies, the Italian offensive over the Albanian border was not. Mussolini had made the subjugation of Greece a cornerstone of his foreign policy, publicly labelling Greece 'a vital enemy of Italy and it's expansion.' Ioannis Metaxas, the leader of Greece, was well aware that the Italians would invade and it was virtually guaranteed that they would do so from their Albanian territory. 82 million drachma were spent on defences on the Albanian border with over 851 million drachma spent on fortifying Northern Greece between April 1939 and October 1940.

Despite all of these factors in favour of the Greeks, it must be recognised that at the beginning of the campaign it looked extremely likely to Metaxas that the Italians would succeed. They were much better equipped than the Greek army and outnumbered them by over 30,000 troops at the beginning of the campaign on the Epirus front. This pessimism was not shared by the population of Greece at large and the soldiers at the front. The Greek army was not well equipped but it had a huge amount of enthusiasm and optimism at their prospects at repelling the Italians and morale was extremely high compared to the Italian troops. This morale transformed the campaign as the Greeks fought ferociously for every foot of land. A captured Greek officer summed up the Greek attitude with the phrase 'We are sure that we will lose the war, but we will give Mussolini the spanking he needs.'

The French army, by contrast, suffered from low morale stemming from an intensely outdated and aged leadership which very much believed in antiquated tactics from the Great War. The French army was woefully unprepared for the sophisticated tactics and advanced weapons of the German army. We must also remember that the comparatively fast French surrender was decided by the political elite, not the population at large; many military officers such as Charles de Gaulle and Allied leaders such as Winston Churchill pushed for France to continue fighting as long as possible like the Greeks would do in 1941 but were overruled.

The geography of Greece, the high morale of the Greek army and the poor leadership and performance of the Italian troops made the campaign in Greece a much greater slog than the campaign in France which hugely extended the timescale. The Greeks not only repelled the initial Italian invasion in October 1940 but an Italian counterattack in March 1941. The Greeks had repelled the Italians but were unable to repel the Germans who invaded from Bulgaria and southern Yugoslavia during April 1941.