Difference between boost::MPL and boost::fusion

I'm new to boost::fusion and boost::mpl libraries. Could anyone please tell me the main difference between these two libraries?

Until now I used only fusion::vector and few other simple things. Now I want to use fusion::map or MPL::map but I don't know how to choose the right one.

I need map simple type to complicated type (type alisa). Currently I have following snippets and both works exactly I need to.

boost::fusion:

typedef boost::fusion::map<
    boost::fusion::pair<AliasNames::test1,int>,
    boost::fusion::pair<AliasNames::test2,double>,
    boost::fusion::pair<AliasNames::test3,float>
> TmapAssociations1;

typedef boost::fusion::result_of::value_at_key<TmapAssociations,AliasNames::test1>::type t;

boost::MPL:

typedef boost::mpl::map<
    boost::mpl::pair<AliasNames::test1,int>,
    boost::mpl::pair<AliasNames::test2,double>,
    boost::mpl::pair<AliasNames::test3,float>
> TmapAssociations2;

boost::mpl::at<TmapAssociations2,AliasNames::test1>::type t2;

Is there any difference between MPL and fusion? Are there any scenarios where one library is preferred over another one?

Thanks for reply.