Depends on which 'Early modern period' you mean. If it's the mid 19th century, Ottoman and European armies were pretty similar, since they had been westernized their army. However, I assume you mean the 18th century where most defeats happened in the later period of that century

It's radically different, to say the least. While European countries are centralizing their armies, the Ottomans decentralized their army instead, using provincial armies and irregulars led and maintaned by provincial leader/governor and mercenaries. The Janissaries has been corrupted as this point, due to the law laxation in the 17th century to increase their numbers. While the decentralization process relieve the burden on the central government and the standing army and increasing primarily the defensive capabilities of provinces (as demonstrated in the campaigns of early 18th century where the Ottomans most of the time emerged victorious), it weakens the Ottoman military capabilities as a whole, as most troops are inexperienced irregulars and mercenaries. The campaigns against Russia and Austria in the late 18th century demonstrated this, as most provincial troops are inexperienced and unused to disciplined European warfare due to the long peace of the Tulip Era and the Ottoman's missing out on developments of the 7 Years War. Unfortunately for the Ottomans, the successful policies and decisions of the 16th and 17th centuries eventually created the nemesis of the system: successful local families who excelled within the Ottoman military administrative tradition and used it for their own benefit. In this regard the empire was out of step with Europe, where absolutism was on the rise and strong kings were centralizing their power in nation-states

Reform efforts are done throughout this era, and some successful, like the reform on the artillery corps (which remains to be the best part of the army well into the 19th century) and temporary curbing of Janissary ranks of the 1750s. However a successful reform effort on the entire military had to wait until the creation of Asakir-i Mansure in the 19th century