difference between arraylist and dictionary in c#

1. Dictionary stores the KeyValue pairs. It is a generic collection class, which means there is Type safety. Generic types are particularly efficient in case of value types as they avoid boxing and unboxing. The corresponding non generic collection class is HashTable.

 

2. ArrayList is a non generic collection class to store items. The corresponding generic collection class is List which is preferable for the same reason mentioned above.

Instead of array list you should use List<>. Thats generics