Hi,

I think your question is very general. What do you mean by "medical devices" ? Or which type of drugs do you mention? For  example ,please check the following link that related to FDA guidance only for Botanical drugs. 

http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm070491.pdf

It is very general. I am not specifying any specific medical device nor a drug. In general I want to know the difference

OK. There is a very good section in "Clinical Trials, A Methodologic Perspective" by S. PIANTADOSI, second edition, 2010:

Page 74 - 4.3.2 Are Devices Different from Drugs? 

In summary, he mentions these differences:

• "First, the action of most devices is physiologically localized rather than systemic."
• "Second, devices are often constructed of materials that have been tested in similar biological contexts and whose properties are well known."
• "Third, devices typically operate on physical, chemical, or electronic principles that are known to be reliable because of previous testing or evaluation outside human subjects."

For discussion, please check the book. 

I also suggest you to read whole section of 4.3 Medical Devices (Page 72 to 76), which you will find all answers you want to know. (The same book.)

if your inquiry targets European,legislation, a good source is:

  http://www.ema.europa.eu/ema/

good luck

SR

In the U.S., regulatory pathways differ somewhat for devices, biologics, and drugs. And they differ for laboratory tests, a topic that is now under consideration for revising pathways at FDA. Devices in particular, often do not follow the familiar phase I, II, III clinical trial pathway of drugs.  Device trials may have no phase assigned. This is apparent when looking at trials registered on clinicaltrials.gov.  There are also differences in the options for abbreviated pathways to market and special designations between drugs and devices.  For example, an innovation pathway exists for devices and humanitarian device exemption pathway; while breakthrough, fast-track, and accelerated approval pathways exist for drugs.  Best to read about it at the 3 divisions of FDA's website.  

Regulations for medical devices and drugs are very different. In Europe launching of medical device requires to demonstrate its accordance with the essential requirements, safety and performance. Accordind to medical devices classification (level of dangerousness), it is madatory to conduct a series  of tests following harmonized standards. Then an audit is performed by a notified body to allow the manufacturer to apply CE marking. A postmarketing follow-up led by the manufacturer is always madatory. The clinical studies are the ultimate demonstration of a medical device efficacy and clinical study are madatory whatever the class of medical device to obtain the CE mark as it is rated by the new directive 2007/47/CE.

FB

The regulations for investigational drugs and investigational devices are not the same, though both are regulated by the Food and Drug Administration (FDA).  The regulations, guidances, and FDA warning letters can be found on line at http://www.fda.gov/.

regarding regulations in india

at present,except for needles and syringes medical devices are not covered by drugs and cosmetic act 1940.

SBMT set up under DRDO has formulated a proposal for setting up IMDRA,but guidelines are yet to be formulated.

all the general principles for drug clinical trials may be considered and decided on by one to one basis by the regulatory authorities

these information is from whitebook relevant to clinical research in india indian gcp and schedule y   by cdsa