system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can a battle be a called "tactical victory" for one side, but a "strategic victory" for the other side? What is the difference, and who actually won?
gpt
Generally, a tactical victory means a victory on the small-scale, while a strategic victory is on the large-scale. 

Imagine that it's WWII again, and Germany and Russia are engaged in war. At a city on Eastern Front, the Germans and Russians have a battle. This is a hard fought battle, but the Germans win after pulling in reinforcements from elsewhere. The Germans have won a tactical victory. The Germans then take the city.

However, by pulling in reinforcements from elsewhere,  the Germans have weakened themselves at other points along the front. This allows the Russians to advance and break through at several other points. This allows them to completely surround the city, trapping the Germans there. The Russians have thus won a strategic victory.