In terms of definitions, the difference is that the Constitution was ratified first and the Bill of Rights are the first 10 amendments that were added to the Constitution.
In terms of their content, the major difference is that the Constitution as a whole sets up our system of government. By contrast, the Bill of Rights is entirely a negative document in that all it does is to lay out what the government may notdo.
The bulk of the Constitution is concerned with saying what the federal government can do and how it will be set up. To be sure, there are prohibitions on things like the creation of ex post facto laws. But for the most part, the Constitution does things like saying how many houses will make up Congress, what powers Congress will have, what powers the President will have, and other such things. It is the blueprint for our system.
By contrast, the Bill of Rights simply sets out a variety of things the federal government may not do. It may not, for example, infringe on freedom of speech. Its officials may not carry out searches and seizures without warrants. It cannot deprive people of their life, liberty, or property without the due process of law. All of these are negative restrictions on government while the Constitution proper is more oriented towards setting up the government.