Certificates on raw materials refer to the respective futures of raw materials, such as oil. In the framework of the so-called rollover is sold the expiring futures and the amount of money in the next due future invested (or rolled). The price difference between the individual contracts will be balanced by the fact by rise or fall in the participation of the certificate. A comparison can be found here. Funds that put the capital of investors in securities by providers who are active in the commodities sector, are known as commodity funds. With these investors through the use of different instruments can seize opportunities offered in global commodity markets. It is possible, on the one hand, to participate in positive developments in the commodity markets, on the other hand you can benefit but also by negative price trends by setting temporary short positions.
You can find the different offers among other things here. Without wanting to evaluate these investments, they completely differ from direct investments in oil and natural gas sources. An oil certificate not invested oil or its source, for example, in the raw material, but is based on the prices of oil futures, which are traded on the Futures Exchange. The investor is not directly on the asset system oil or natural gas involved so tradable securities, but only on their derivatives. As pointed out the renowned Professor Dr.
Karl-Georg Loritz in several essays, this is dependent on the interactions of the stock exchange here, without directly to influence the actual asset. You should leave this field specialists.