Salesforce has multiple product offerings like Sales Cloud, Service Cloud, Marketing cloud which help you to implement a particular business flow.
To Market your product, you can use Marketing cloud, For Selling to customer, you can use Sales cloud.
Now once you have decided what product offering you are going to use, you have option to buy different edition.
Editions in salesforce is same products which are different in features. You may think of it like car models. A same car lets say HONDA CITY may have different models which are different based on features ex. lxi, vx,i ldi, etc.
Similarly, lets say if we choose Salesforce Sales Cloud we have different editions available. like Enterprise, Professional, Unlimited etc. These editions differ based on features they provide hence they have different pricing. You can see the details here.
Organisation (can be interchanged with Environments)
Now once you decide an edition to buy, you will customize it. Now in real world scenario, you will have a development and deployment process in place.
So, you will be required to develop the functionality, test it and then make it available to the users. That is where Environments come in picture.
With each salesforce product edition, you will get multiple Environments which you can use to develope and test you code/customization.
These environments are of several type:
- Developer/Developer Pro/Config only Sandboxes
- Full Sandboxes
- Partial Sandboxes
Lets say you get 10 Developer Sandboxes, 1 Production Org, 1 Full Sanbox, 1 Partial Sanbox with the edition you bought/licensed.
You and other developers may develop the code in Developer Sandboxes/Environments, Move it to Partial Sandbox/Environment for merging and testing, Move it to Full Sandbox for Performance testing and User Acceptance testing and then to Production i.e live to end users.
You can read more about sandboxes/environemnts here
Yes, If you have access to production, you can create environments upto limit specified by salesforce based on edition you are using.