system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what is the difference between "tactical" and "strategic" in war?

I've read texts about battles that went like: "this was a tactical victory but a strategic defeat" or the other way around.  
What are tactical vs. stategic nukes?  
What is a tactical weapon battle / victory / defeat ? Same for strategic.
gpt
Tactics = The actions taken to accomplish a goal or task.

Strategy = Figuring out what your goal is and the general path to get there.

For war, using World War II.

Strategy was the U.S. military generals deciding to fight and win the war in the European theatre first while just performing holding actions in the Pacific against the Japanese.

Tactics were the Army platoons sending firing squads on flanking movements around German positions.

Operational is the level in between. Operations are executed using tactics to accomplish the strategy. So Operation Overlord (the D-Day landing) used tactical movements to accomplish an operation in support of a strategic goal.

Edit - Just read the fine text. A tactical nuke is low-yield meant to accomplish a tactical action such as taking out a single unit or stronghold. Its use would be the equivalent to fighting a skirmish or battle. A strategic nuke is high-yield meant to accomplish a strategic goal, such as breaking an enemy nation's will to fight.

A tactical victory but strategic defeat would be fighting rabidly over a position, losing most of your forces, but claiming victory in the battle. Except now you've lost 80% of your military forces and the enemy has another army marching 300 miles north of you towards your nation's capitol. You won the battle (tactical), but screwed yourself over for the overall war effort (strategic).