When there are rules in a game, it allows events to be conducted fairly and the winner can be selected based on skill levels. The Olympic Committee or other Sports Associations may tweak or vary the rules of a game over time, but the game will still be the same unless the changes are substantial and Demonstrate Different Skills.  

**Examples:**  

**Eg 1:** 100 Meter Dash versus 200 Meter Dash versus Marathon are considered separate events requiring separate skills, but running with blue clothes versus running with green clothes will be the same event.  

**Eg 2:** Playing Basket Ball with team size of 12 versus team size of 14 will be the same game, but replacing the Basket with a large goal makes a new game like Hand Ball.  

**Eg 3:** Playing cricket over 5 Days with 4 innings versus 1 Day with 50 overs each side has substantial Differences.  

**Eg 4:**  Tennis on grass court versus clay court is almost same, but changing the court to a small table makes a new game Table Tennis with associated equipment.  

**Running versus Walking:**  

These are totally Different with Running always being faster than Walking; No one would ever Walk in a Running Race and finish last while the others would have run and finished much earlier. Hence Walking is a separate event where running is not allowed. Walking fast skills involve Posture, Arm Motion, Stamina, Stride, etc. Running involves reacting to the gun fire, leaping start, acceleration, etc.

**Swimming:**  

In swimming, the [strokes][1] have unique challenges and unique advantages, making the Differences substantial and hence considered separate events.  

It seems that there were many other strokes and variations earlier in Competitive Swimming, but these were gradually removed, according to [Britannica][2] 

Similar to the Point about running with specific colours of clothes, there was a time when swimmers used advanced high-tech body-suits and broke world records, but these advancements were banned, yet the event still remains the same because these changes in rules are not substantial.  

Certainly, there have been Debates, which resulted in Changes in rules over the years. Currently, the status is that the Strokes require separate skills and accordingly, separate events.  

  [1]: https://www.swimmingworldmagazine.com/news/comparing-and-contrasting-the-four-main-swimming-strokes/
  [2]: https://www.britannica.com/sports/swimming-sport