Chocolate Chip Cookies

So, I haven't always been the best at cooking, or baking. Based off of that, I chose somewhat of an easy, but also difficult book, called "Ultimate Comfort Food". The last time I tried to make Mac & Cheese, I accidentally kind of set it on fire, so I thought for this assignment, I'd start with something simple. Something I could also get help on if things went a little.. messy. So, I chose chocolate chip cookies (cause, who doesn't like those?). It's a very simple recipe, as well as a beginner one.
To begin with, I gathered up everything I need:

3/4 cup of butter, softened

2/3 cup shortening

1 cup sugar

1 cup packed brown sugar

2 eggs

2 teaspoons vanilla extract

3 1/2 cups all purpose flour

1 teaspoon baking soda

1 teaspoon salt

2 cups (12 ounces) chocolate chips

(The picture only has some of the supplies, it took a while to find the rest)

Now, this recipe will make about 3 dozen cookies, and that;s quite a lot (but hey, I don't mind at all).

So, the first step of this recipe is to cream shortening, butter and sugars until light and fluffy into a large bowl (p. 282). Then, beat in the eggs and vanilla. After that, combine the rest of the ingredients (except the chocolate chips) and throw that mixture into the bowl as well, then, mix well before adding in the chocolate chips.

This step turned out to be sort of tricky for me. We don't really have any mixing machine, so I had to do it by hand with a rather weak wooden spoon. The mixture was thick and hard to stir, but eventually, I got a hold of it.

After mixing them all together, I added the bag (we got a large) of chocolate chips (I wanted it to be extra chocolaty). Then, the next step is to chill in the fridge for at least an hour.
Just to be careful, I left it in the fridge for an extra 15 minutes before taking it out. The next step after this was to lay the cookie dough into 1/4 cupfuls 2 inches apart onto greased baking sheets. Now, the author warns to be very careful with how I placed the cookies, and to be exact, because this recipe made the cookies turn out extremely large and fluffy (p. 283). So, JUST to be exact, since I sort of suck at cooking, I grabbed a ruler from my room and used it to measure the dough and placement EXACT (I know I know, I'm too worried). After filling up almost 4 baking sheets, the next step was to place the cookies in the oven and bake at 375 degrees for 13-15 minutes, or until golden brown. So, I shoved them into the oven, and waiting for 20 minutes before taking them out.

Now, make fun of me all you want, but I forgot to put on a glove, so I burnt the inside of my thumb and ended up dropping a rack. BUT, it's okay! Only a little under half the cookies didn't survive, but I still had just the right amount to enjoy.

The cookies looked delicious! But I think I did something wrong, because they didn't turn out very big and fluffy at all, but they were DEFINITELY chocolaty, due to the extra chocolate chips. So, following the instructions, I let the cookies cool for a few minutes before removing them from the baking sheets.

As you can see, they look pretty edible! So, at least I didn't mess up too bad. And, trust me, they were SO good!

But, my question is, what if I ended up using baking powder instead of baking soda? I used the last of the baking soda, and I was wondering if there was any difference between the two?