HL7 v2 and V3 comparison.

There are tons of articles on the web about HL7 v2 and v3 comparison. This is just one of them.

HL7 has been a dominant force in the Healthcare IT systems and continues to remain so primarily with its messaging standard v2.x. With the introduction of v3, HL7 has taken a major step to overcome the limitations or sometimes dead-ends in v2.x implementation. Below is a quick summary of those differences from an Healthcare IT implementation perspective. There is also a link to a very good presentation on the differences.

Differences between HL7 v2 and v3:
HL7 V2

• Not “Plug and Play” – it provides 80 percent of the interface and a framework to negotiate the remaining 20 percent on an interface-by-interface basis
• Historically built in an ad hoc way because no other standard existed at the time
• Generally provides compatibility between 2.X versions
• Messaging-based standard built upon pipe and hat encoding
• In the U.S., V2 is what most people think of when people say “HL7″

HL7 V3

• Approaching “Plug and Play” – less of a “framework for negotiation”
• Many decades of effort over ten year period reflecting “best and brightest” thinking
• NOT backward compatible with V2
• Model-based standard built upon Reference Information Model (RIM) provides consistency across entire standard
• In the U.S., Clinical Document Architecture (CDA) is what most people in the U.S. think of when people say “HL7 V3″
• V3 messaging hasn't taken off much when compared to the V3 documents adoption.
  

Video on HL7 v2 and v3 comparison:

http://www.neotool.com/download/videos/Dec4_Fast15_HL7_V3_Insights.swf

Useful links on HL7:
http://www.hl7standards.com/blog/