“Although” is a conjunction (linking word) that expresses the idea of contrast. It means “in spite of the fact that.” It is usually used when the condition given is positive, but the outcome or result is negative.
Although everyone showed up on time, the meeting began 15 minutes late.
“Though” means the same as “although,” but it is used slightly differently, in a poetic or more informal way.
Though the stars may fall from the sky, I shall remain loyal to my true love. (poetic)
I liked the shoes. I decided not to buy them, though. (informal)
“Even though” is an expression that is stronger and more emphatic than “although.” It is often used when the condition given is negative, but the outcome or result is positive.
Even though it was way past quitting time, the Grammar Godmother diligently sent out her writing tip of the day.