Data structures
In my view, there are only three significant ideas which must be mastered to write interesting programs.
a) Iteration - Do, While, Repeat, If
b) Data Representation - variables and pointers
c) Subprograms and Recursion - modular design and abstraction
At this point, I expect that you have mastered about 1.5 of these 3. It is the aim of Computer Science to finish the job.
Data types vs. Data Structures
A data type is a very well-defined collection of data along with a well-defined set of operations on it.
A data structure is an actual implementation of a specific abstract data type.
Example: The abstract data type Set comprise the operations EmptySet(S), Insert(x,S), Delete(x,S), Intersection(S1,S2), Union(S1,S2), MemberQ(x,S), EqualQ(S1,S2), SubsetQ(S1,S2).