VC, PE, RA together are called private investment.  VC generally invests in early new technology, such as IT, biotech, pharmaceutics, etc.  Currently, clean energy is a pretty hot area.  Since VC invests in really early stage companies or only ideas, it is a very risky business.  An investor could lose all his money or get 10 X return.  Pre tech bubble, VC made gigantic money.  Since then, VC as a group has yet to make a decent return compared with public equity (stock market);  However, it is making its move.

PE has a large range, from large leverage buyout (LBO) to small buyout, from distressed bond investment to vulture (take whatever you can from a bankrupt company), etc.  PE normally invests in late stage or mature companies compared with VC.  Even though they can take public companies to private but they mainly invest in private companies.

RA includes private real estate and real assets.  Private real estate is easy to understand, they invest in large buildings, apartment, malls, land, hospital building, warehouse, etc.  Residential real estate investment is only a very small portion of private real estate.  Last a few years, even though residential real estate has been tanking, private real estate has been generating very good returns; however, it starts to cool down also. 

Real assets mainly refer to forest, paper, mining, mineral, oil and gas, etc. It is part of RA. 

It is hard to really differentiate among VC, PE, and RA in real life.  Sometimes, they are interchangeable.  For example, Blackstone, it is an oil company so it can be called a RA but it is also a LBO, so it can be called a PE. 

All these are risky, cyclical business.  No one is better than the other.  It depends on manager’s skills and timing.  Because of the high risk, these investments are not for everyone.  Generally, the investors have large capital, either high-net-wealth individuals or institutions.  If you can get in, congratulations!  You are rich!