How can I move all of my photos from Iphoto to Photos?

Launch Photos with the option key held down. From the resulting dialog, choose your iPhoto Library. Photos will make a new Photos Library with your iPhoto media. Your iPhoto Library will not be changed, though it will be renamed.

How can I move all of my photos from iPhoto on an old MAC laptop to my new MAC Photos?

You mean like Smart albums?

Create Smart Albums to group photos automatically in Photos on Mac - Apple Support

Do you have an external hard drive?

What is your new computer? You might be able to use target disk mode:

Transfer files between two Mac computers using target disk mode - Apple Support

Could this be the existing Photos Library?

What size is the Photos Library it created?

Try to start with the option key held down and Launch the new Photos Library.

Photos is a database. Any database is like a sewer: What you get out of it depends on what you put into it. So what kind of classifications are you talking about?

Just like I said above:

Launch Photos with the option key held down. From the dialog, choose your iPhoto Library. Photos will create a new library from your iPhoto media.

Can you give me a few more details. IPhoto is on my ole MacBook Pro. I have thousands of pictures I want to move to my new Mac. Sorry I don't have a lot of experience moving data

I have a macOS Catalina 10.15.7

I have an eternal drive that I used to back up old Mac

How do I get the pictures transferred off the external drive to the new MAC?

I read the instructions for transfer files between 2 Mac computers but don't understand them.

When you got the new Mac did you use Migration assistant to get the files from your backup? Your library might have already been transferred.

I am not sure. Assuming I used the Migration assistant but can’t find that the photos from iPhoto transferred to new Mac. ? How would I find the Library if they transferred?

Look in your Pictures folder.

Or launch Photos with the option key held down, and see if it shows up in the dialog that appears.