There are several types of Open Source licenses. Template Licenses (Apache, BSD, MPL) may be used by others simply by changing the names. These are further divided into Academic vs. Reciprocal Licenses. Academic Licenses originated in institutions of higher learning (Berkeley, MIT) which wanted to deliver the widest circulation achievable. In the terms of an Academic license there are no real restrictions on use, rewriting, and dissemination (CCH).
Reciprocal Licenses such as the GPL require that anyone distributing the software offer the source code for the entire work as distributed, including all changes (GPL).
In explaining the differences between the GPL (GNU Public License) and other open-source software licenses, we need to first look to property law and the common law concept of licensing (McKeough, Bowrey, & Griffiths, 2002). In the most basic terms, a license is a unilateral permission to use someone else's property. In this case the property is not real property or a chattel but an Intellectual Property. Thus the license is a right to make use of a copyright material (Van Caenegem, 2001).
A license may be granted within a contract (Cornish, 2000), but a license is not a contract in itself. We have to ask, “What is a contract?” Although simplified, a contract is a promise that is legally binding (Carter & Harland, 2002). The three pillars of a contract in common law are:
- Acceptance, and
A bare license can be revoked as it is not a contract and there has been no consideration (Ricketson, 1999). The court could recognize the user’s dependence on the software to act as a substitution for consideration. This would prevent the license being revoked (Rosen, 2005, p. 56).
So GPL is not a contractual arrangement and may not be made into one. To see how this affects an issue of a license under property, it is necessary to look at the Copyright Act (“CA”). This statute defines four requirements for copyright protection:
(i) Created by a ‘qualified person’ – ss32(4), 84, 184 CA.
(ii) Subject matter – ‘works’ and ‘subject matter other than works’ – ss10, 32, 89-92 CA.
(iii) Material form – ss10, 22 CA, and
(iv) Originality – s32 CA.
The GPL license states that redistribution of any “derived” works needs be published under the terms of the GPL. Thus any software created using a GPL base must remain under the GPL. This is the "traditional" format used in open-source licensing. The objective of which is to ensure that an open-source program will always stay open-source.
A derivative work is an original work by an author that is based on a pre-existing work. The author of the derivative work can license and distribute the derivative work provided he has license for the pre-existing work to create a derivative work from it and to distribute that derivative work (Ricketson & Richardson, 2005).
The GPL can be firstly distinguished from another of the “Open Source” software license structures, the “FL - project-open "Free License"”. FL software is distributed openly without cost to use and modify. It is however classified as commercial software, but the license fee for use and modification is given without consideration. This is where FL deviates from the GPL. Whereas GPL provides the free distribution of any derived software, FL requires consideration for this right (Garnsey).
The GPL is a true copyright license: a unilateral permission, in which no obligations are reciprocally required by the licensor (Cornish, 4th ed). FL is thus a licensing agreement that is issued to end-users without consideration, but is assigned under contract for the purpose of development or distribution.
The next distinguishing feature of the GPL from the FL is that of ownership. The GPL allows for open redistribution of the source code under the sole condition that derivative works remain covered by the GPL. FL license terms allow the rights of distribution to remain in the full control of the “maker”. The FL thus can create sole property rights and ownership, while the GPL is a “work of joint ownership”.
In the terms of the FL, the developers of the work are each owners they can each license the entire joint work to others as they individually see fit (Van Caenegem, 2001). The rights are assigned under contract. GPL creates no such contract; the work is a collective work, each of which is under its author’s respective license, and thus by the terms of the GPL must also be distributed under the GPL (CCH, Australian Industrial and Intellectual Property).
Most Open Source projects are joint works (Rosen, 2005) with no reason for the assigning of copyrights. In the case of a collective works, the collector is the author and can license and distribute the sole portion that has been created, but only with license to distribute from the authors of the constituent pieces themselves. In the GPL this is an implied license attached to the chain of rights. Proprietary Rights and Assignments of the GPL come with an implied licence of the GPL terms.
The GPL, condensed to its core, (Rosen, 2005) consists of an agreement to: copy, modify and redistribute the software, whether modified or unmodified, freely. “If you redistribute it, in modified or unmodified form, your permission extends only to distribution under the terms of this license. If you violate the terms of this license, all permission is withdrawn.”
Thus the primary factors that distinguish open source software licenses are basically no more than terms of legal art. In all cases the moral rights are not assigned.
 s22 CA.
 ss10(1)”work of joint authorship”, 35(2), 35(3), 35(4), 35(5), 35(6) CA.
 Community ownership: Bulun Bulun v R & T Textiles Pty Ltd (1998) 157 ALR 193 (MBG 2002 at pp129-138).
 s196(1), 197 CA
 Loughlan, P (2001) 12 AIPJ 189