What's Western Philosophy?
There are a lot of European philosophies, and there are a lot of philosophies from outside of Europe. Trying to corral everything into Western and Eastern with some set of neatly definable characteristics is an exercise in futility.
There are, however, quite a few common threads. Nothing that you can use to gather it all under one banner, but there are some recurring themes that crop up more in Europe than eslewhere, and vice versa.
If we take Eastern philosophy to mean the philosophies of southern and eastern Asia, then one of the most common themes is a Hindu influence, via Buddhism. Notice I say a common theme, not a universal theme, because there is plenty of classical Indian philosophy and religion before Buddhism, such as the Vedas, and there is plenty of classical Chinese philosophy before the arrival of Buddhism in China; Confucius likely lived around the same time as the Buddha, but classical Confucianism is essentially pre-Buddhist because it arose before Buddhism got to China. That being said, Buddhism made its way from India into Southeast Asia, China, Korea, and Japan, among other places, and exerted a strong influence on the philosophical traditions it encountered. So in many of the philosophies of the region, you have a strain of Hindu influence, Buddhism being a heterodox school of Hinduism.
Another difference is the attitude toward dialectic. Western philosophy is heavily focused on disputation, heavily dialectical, more so than most of the philosophies of Eastern and Southern Asia. This point is far more tenuous than the last because there are more exceptions. Indian philosophy has a lot more in the way of disputation and closely-reasoned argument with attention to semantics than Chinese philosophy, for example. It’s still based on Vedic hymns and poems you can find in the Upanishads, which take the form of hymns and stories more often than treatises, although there are some treatises there. In fact, the arrival of Buddhism to China from India provided the stimulus for traditional modes of thought in China to be finely articulated in ways they were not before, because Buddhism introduced a more precise dialectical mode of reasoning to China. Another exception is Mohism. The Mohists, who made a lot of advances in science, mathematics, and engineering, heavily emphasized disputation as their dominant mode of reasoning and pursuing truth, and Mohism even gave rise to a further school called Ming Jia, or the School of Names, which focused on semantics. This focus on semantics became incorporated further down the line into Neo-Confucian thinking, and the “rectification of names” was even interpolated into the Analects; some scholars think that this was an interpolation of specifically Mohist thought.
The exceptions, however, often prove the rule. During the 1800s, certain Chinese intellectuals, who wanted China to catch up to Europe and modernize, began searching historical Chinese philosophy for something similar to Western thought. What did they find? Of course, Mohism. The Mohist school was long dead by the 1800s, but the fact that Chinese scholars of the time recognized its similarity to Western thought should tell you something about the predominance of dialectic in Western thinking. Mohism was dialectical, yes, but it died out because it simply couldn’t survive in its cultural context. You could say something similar about the Greek influence on Islamic philosophy. Avicenna’s Floating Man argument postulated something like Cartesian dualism, centuries before Descartes, and this was a result of the Greek influence on Islamic thought at the time, but the Greek dialectical component of Islamic philosophy could not survive its inevitable conflict with Islam itself. It was only in Europe where the dialectical method really flourished.