PDCA (Plan-Do-Check-Act) Cycle is an iterative methodology used for continuous product and/or process improvements. It is specifically useful for testing improvements on a smaller scale before full scale implementation. It is also known as Deming circle, Shewhart cycle and PDSA (Plan-Do-Study-Act).
OODA (Observe-Orient-Decide-Act) Loop is a four step decision making process that is used to assimilate available information and then decide on the next steps. The steps can be repeated again as and when more information becomes available.
An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Mohamed Asif and Subodh Tripathi.
Applause for all the respondents - Brij K Chandiramani, Aji Lal, Subodh Tripathi, Sahil Anand, Mohamed Asif