There's a difference, right? When I read, I don't like wondering what you meant. I want you to spell it out to me.
Writing is about making it easy and enjoyable for the reader. I usually tell my students that when they plan a paragraph, they are signalling a road for the reader to have a pleasant journey.
Extending this journey metaphor...
"Think of punctuation and mechanics in terms of driving your car. Punctuation and mechanics provide direction and signal the information to which you need to pay attention. Without punctuation and mechanics, phrases and sentences would run into each other and would be unclear, and your writing would go virtually nowhere. The purpose of punctuation and mechanics is to make your meaning clear by telling the reader when to pause, when to stop, when to take notice, etc" (I found it here.)
The power of punctuation is better explained by examples. Then you need some general rules. Above all, you need exercises!
The Purdue University website has a good menu to cover the punctuation you need to know.
If you find that too much, you may wish to do a quick quiz instead.
In the middle of your writing, you may need to consult a guide about specific punctuation marks. This one is quite comprehensive. This one is faster and has exercises.
A quick cheat-sheet to have near you while you write could be this Oxford site.