What is the difference between these two scripts?

Questions & Answers
1

I am following a tutorial to make a simple 2d shoot 'em up. If I type out the script myself it does not work but if I copy and paste the script everything works as expected. The non-working script never seems to call OnTriggerEnter2d because I tried putting in print statements but they never appear. The only differences I can find are different placement of brackets, spaces and comments but I see no reason for differing behavior. This has been driving me up the wall and I would greatly appreciate any explanation for the differences in behavior between these 2 scripts.

Not working:

using UnityEngine;

public class HealthScript : MonoBehaviour
{
	public int hp = 1;
	public bool isEnemy = true;
	public void Damage (int damageCount)
	{
		hp -= damageCount;

		if (hp <= 0)
		{
			Destroy(gameObject);		
		}
	}

	void OnTriggerEnter2d(Collider2D otherCollider)
	{
		ShotScript shot = otherCollider.gameObject.GetComponent<ShotScript>();
		if (shot != null)
		{
			if (shot.isEnemyShot != isEnemy)
			{
				Damage (shot.damage);
				Destroy(shot.gameObject);
			}
		}
	}
}

Working:

using UnityEngine;

public class HealthScript : MonoBehaviour
{
	public int hp = 1;
	public bool isEnemy = true;
	public void Damage(int damageCount)
	{
		hp -= damageCount;
		
		if (hp <= 0)
		{
			Destroy(gameObject);
		}
	}
	
	void OnTriggerEnter2D(Collider2D otherCollider)
	{
		ShotScript shot = otherCollider.gameObject.GetComponent<ShotScript>();
		if (shot != null)
		{
			if (shot.isEnemyShot != isEnemy)
			{
				Damage(shot.damage);
				Destroy(shot.gameObject); // Remember to always target the game object, otherwise you will just remove the script
			}
		}
	}
}
2

Line 17 : OnTriggerEnter2D , capitol D . Always check spelling, capitols, and punctuation.