Both sides had advantages.
The North had more people, way more money, more railroad track laid down to transport troops and supplies, more factories to make uniforms and weapons, and international recognition as a sovereign nation.
The South had home court advantage (most of the fighting was done in the South) so they knew the land and the people.
They had more to lose, so they fought oftentimes more desperately.
They had forced free labor (slaves).
And in the beginning of the war they had better generals and an excellent cavalry as Southerners were way more rural than the urban Northerners.
