if want to reduce the complexity of our program then we use 
templates instead of base class. mainly it is used in 
larger programs.

Template is used when you have to use different data types  
in a single Class.In run time compiler alloate memory for 
data.Template is also used to reduce the complicity of any 
program,But in base class Complexity is  high in larger 
program,because you have to create different class for 
passing different data types.In template you can create 
only one.

templet is in the form of tag but classes are simple.

for Container kind of code

Template is a better approach than using of a base class if:
1. Multiple copies of code for different data types with 
the same logic.
2. If a set of functions or classes have the same 
functionality for different data types
Then, a class becomes good candidates for being written as 
Templates.

   One good area where this C++ Class Templates are suited 
can be container classes. Very famous examples for these 
container classes will be the STL classes like vector, list 
etc., Once code is written as a C++ class template, it can 
support all data types. 

Though very useful, It is advisable to write a class as a 
template after getting a good hands-on experience on the 
logic.

You can judge the need of Template and base class based on
following rule of thumb..
When operation(Method) doesn't affect on changing the data
type, use template.for ex when you want to write the stack
class of different data TYPE(int, bool,flaot) PUSH & POP
method doesn't affect on changing the data TYPE so in this
case you have to use TEMPLATE instead of Inheritance. 
When operation(Method) does affect on changing the data
type, use Inheritance(base class).