Well, besides of the similar or bigger numbers. I think that the combined arms way to fight from the Sicilians and the lack of the C.& C issues of the OTL Crusading Armies, would mark the difference against the Ottomans. C&C issues, ones which stemmed from some of the Crusading Aristocrats leaders mindset (same one that caused the French debacles before their English opponents and quite more relevant, the 'Golden Spurs' one, when faced with the Flemish rebels
Very much so! Especially since the Sicilians field pike-heavy armies, in contrast to knight-heavy armies of the Crusaders. Then it is how the sicilian army was evolved: Alexios Philanthropenos built that army, with the expertise he had from Asia Minor and from fighting turkish cavalry there. Emphasis was given on feigned retreat and ambush and then he developed pike blocks to stop heavy cavalry. This unique combined arms approach is very suitable to defeat early ottoman armies.
Then it is the matter of naval power. It is true that the Byzantines holding Gallipoli after the Savoyard Crusade didn't accomplish anything. However, they held just the city itself, not the whole peninsula and they had no ability whatsoever to use Gallipoli as an offensive base. But if Alexandros Philanthropenos captures the whole peninsula, restores the 6km justinian wall at the neck and uses is as an offensive base? That's a whole different thing.
The existence of the Lascarid Empire produces another butterfly. Since it is doubtful that lascarid Macedonia and Thessaly will simply collapse, then the pattern of the ottoman colonization in the Balkans will be disrupted. At this point in history, the sustained war effort in the Balkans was immensely helped the settlement of militarized nomadic and and semi-nomadic Turkmen/Yoruk tribes in the balkan lowlands. At this point, the colonizing effort was in the thracian plain, but as soon as serbian and byzantine Macedonia and Thessaly collapsed, tribes moved to the lower Strymon valley, lower Axios valley, Pelagonia and Thessaly. These tribes provided most of the light cavalry used by the Ottomans and did most of the raiding as well. The Ottomans didn't
regularly move light cavalry from Asia Minor to the Balkans back and forth :
usually they operated with local forces.
So, without a lascarid collapse, Murad has two choices: limit the colonizing effort or concentrate the effort even more in Thrace and Bulgaria. If he chooses the latter strategy, there are certain drawbacks. First and foremost, more agrarian peasants are uprooted and replaced by pastoralists. Until the reign of Mehmed II, the tribes didn't pay taxes or at least paid
very limited amounts mostly in booty from raids. From the mid-15th century the Ottomans started the process of the gradual agrarianization and sedentarization of the nomads. By then, they had a lot of sipahis, an expanded Janissary Corps and the Tatars to act as light cavalry. So, more concentrated nomads will mean much fewer taxes for the state.
The other issue is that concentration of nomads will spook the local elites. A fair good number of Byzantine, Bulgarian and Serbian elites were incorporated in the ottoman system and islamized in order to keep their privileges and lands. If more unruly nomads are replacing their peasants and take away their land, they have little reason to be loyal to the Ottomans. That applies as well to the still independent Bulgarian lords north of the Balkan Mountains: they have all the more reason to resist.
Lastly, before Timur arrived at the scene, the Ottomans have some pragmatic restriction on how many tribes they can resettle. Timur's campaigns drove a lot of tribes further west, one tribe replacing the other and a lot of Turkmen crossed to Europe. Likewise, a number of Tatars fled from the Pontic Steppe to the Ottoman Balkans after they were defeated by Timur. The Battle of Terek River is still two decades in the future.