Update vs Modify vs Change – Create vs Add – Delete vs Remove

I am working in a human resources management application and I have to often work with the creation/deletion/updating of people from the web interface.

I'd like to know whether Update, Change and Modify have slightly different meaning and what is perceived as best for describing the operation of changing an already present resource in the database.

I have the same doubt for Add and Create, I actually preferred Add because it is shorter and more immediate however I changed to Create because Add might infer something is already present and needs only to be added (for instance in a group), with Create it is clear we are talking about an inexistent entity which is created for the first time and added to database.

As for Delete and Remove I use this rule:

• Delete = permanent removal
• Remove = non-permanent removal