Curtains and blinds are both very different in how the act and in how they look but ultimately have the same outcome. Curtains do come across much more stylish and can fit in with the rest of the decor nicely if chosen well. They can be used to coordinate with everything else in the room or stand out in contrast. Whereas curtains do come in a variety of styles and texture they are not a useful in everyday life as blinds are. Curtains have the added benefit of adding warmth to a room, they also work as a sound barrier to keep noise inside the room. But blinds make a room seem much larger and fold away easily. 

The price or curtains and blinds can vary a lot due to the material used and the quality of the material. The price may also vary due to the process in which they have to be put in because quite often bought products would have to be custom made which always increases the price. Curtains are often made from linen and luxury products such as that which makes them very expensive, whereas blinds are mostly made from wood or high quality vinyl. This makes them still expensive but far cheaper than most curtains. Installation of both curtains and blinds is not wildly difficult and would be and easy enough D.I.Y. project, but prices can vary on installation so you would have to shop around for the best price.

The amount of light let in by curtains will depend on the the type of material that the curtains are made out of and how transparent it is. Blinds are much more versatile especially the vertical and horizontal blinds as they can be adjusted to allow different amounts of light in at your will.  

In extreme climates more expensive curtains may be required. There are specially backed thermal curtains are available to ensure that the maximum amount of heat is kept in. In these sort of situations blinds would not be very useful as they do not keep in  massive amounts of heat and would almost be rendered null and void in extreme situations.

Another benefit of blinds is that they provide some form of privacy at all times. Curtains only provide privacy when closed, but even when blinds are tilted to let in more light they still provide privacy. When closed both products give you complete privacy from the outside world.

In my opinion the best scenario is having blinds and curtains, but this is the most expensive option of the three. Having both blinds and curtains will allow you to control the amount of light that is being let into the room. It will also keep the room much warmer with the added two layers to prevent heat loss . There will be less noise escaping the room with the added benefit of having some amount of privacy at all times.

Realisticly when it comes to buying curtains and blinds with will all come down to what your budget is and what needs you have, because if you live in a hot country it is not going to be necessary to have big thick curtains. But both are extremely useful and versatile products.