According to the Special Olympics web site (http://www.specialolympics.org/), differ in that:
"Special Olympics and the Paralympics are two separate organizations recognized by the International Olympic Committee (IOC). They are similar in that they both focus on sport for athletes with a disability and are run by international non-profit organizations. Apart from that, Special Olympics and the Paralympics differ in three main areas: 1) the disability categories of the athletes that they work with, 2) the criteria and philosophy under which athletes participate, and 3) the structure of their respective organizations."
The schedules and structures also differ, with the Paralympics taking place alongside the Olympic Games while the Special Olympics take place on their own schedule.The most recent Special Olympic Games were in Pyeong Chang, Republic of Korea, and took place Janary 29 - February 5. 2013, while the most recent Paralympic Games took place in London in the summer of 2012.
I didn't find much in the way of books about the Paralympics, but here are some interesting articles and one ebook about the history and development of the Paralympics:
The Paralympics: official website of the Paralympic Movement
Enos, M., Busse, S., Davis, R., & Megginson, N. (2012). The Influence of Paralympic Game Proposals on Successfully Hosting the Olympics. Palaestra, 26(3), 53-55.
Girginov, V. (2013). Handbook of the London 2012 Olympic and Paralympic Games : Volume One: Making the Games. Milton Park, Abingdon, Oxon: Routledge.
James, Mark, and Osborn, G, (2011). London 2012 and the Impact of UK's Olympic adn Paralympic Legislation: Protecting Commerce or Preserving Culture? The Modern Law Review74 (3), 410-429.
Misener, L., Darcy, S., Legg, D., & Gilbert, K. (2013). Beyond Olympic Legacy: Understanding Paralympic Legacy Through a Thematic Analysis. Journal Of Sport Management, 27(4), 329-341.
Purdue, D. J., & Howe, P. (2013). Who's In and Who Is Out? Legitimate Bodies Within the Paralympic Games. Sociology Of Sport Journal, 30(1), 24-40.
Again, the Marx Library doesn't have many books about the Special Olympics but here are some good articles:
Special Olympics: official website of the Special Olympics.
Conatser, P., Naugle, K., Tillman, M., & Stopka, C. (2009). Athletic Trainers' Beliefs Toward Working With Special Olympics Athletes. Journal Of Athletic Training, 44(3), 279-285.
Foote, C. J., & Collins, B. (2011). You Know, Eunice, the World Will Never Be the Same after This. International Journal Of Special Education, 26(3), 285-295.
Kenny, C. (2011). Partnerships between sporting bodies: The Special Olympics and Euroleague. Journal Of Sponsorship, 4(4), 314-324.
Petracovschi, S. (2012). Representation of the notion of competition in adapted sport by physical education and sports teachers in the centres of inclusive education in Timisoara and in the Timis County. Timisoara Physical Education & Rehabilitation Journal, 4(8), 15-21
Shihui, C., Chunxiao, L., & Yandan, W. (2011). Development of Special Olympics in China: Competition, Inclusion, Research, and Future. Asian Journal Of Exercise & Sports Science, 8(1), 29-38.
Smith, G, Chan, A., and Ford, S. (2009). Sports Commerce and Peace: the Special Case of the Special Olympics, Journal of Business Ethics, 89, 587-602.
Wilski, M., Nadolska, A., Dowling, S., Mcconkey, R., & Hassan, D. (2012). Personal development of participants in special Olympics unified sports teams. Human Movement, 13(3), 271-279.