Two more images on the differences between Queue and Stack

Author: codingEzio

chap04_sequences/README.md

@@ -7,3 +7,6 @@
 - What sorting algorithm is most commonly used when sorting a sequence of ordered values?
 - What search algorithms are possible in a sequence?
 - What is the complexity of many of the common operations on sequences and how is that complexity affected by the underlying organization of the data.
+
+### Stack versus Queue
+> Put all the technical details aside, what you only need to know is that each was built for specific purposes <small>(<u>the data and how we gonna retrive those data</u>)</small>, *stack* is for **LIFO**, whereas *queue* is for **FIFO**.