Difference between Finite Automata and Turing Machine

1. Finite Automata: The finite automata or finite state machine is an abstract machine that has five elements or tuples. It has a set of states and rules for moving from one state to another but it depends upon the applied input symbol. Basically, it is an abstract model of a digital computer. The following figure shows some essential features of general automation.

Figure : Features of Finite Automata

The above figure shows the following features of automata :

1. Input
2. Output
3. States of automata
4. State relation
5. Output relation

2. Turing Machine: It is a powerful model which was proposed by Alan Turing in 1936. The earlier models like finite automata and push-down automata are not considered accurate models because they cannot recognize the simple language. But the turing machine is the most accurate model for personal computers. A turing machine is capable of solving every problem that a real computer can do. There are also some problems which can not be solved by turing machines because these problems are beyond the theoretical limits of computation.

Figure: Turing Machine Model

Difference between Finite Automata and Turing Machine:

Finite Automata	Turing Machine
It recognizes the language called regular language.	It will recognize not only regular language but also context-free language, context-sensitive language, and recursively enumerable languages.
In this, the input tape is of finite length from both the left and right sides.	In this, the input tape is of finite length from the left but is of infinite length from the right.
It consists of a finite number of states, a finite set of input symbols, an initial state of automata, and a finite set of transition rules for moving from one state to another.	It also contains a finite set of tape symbols and a blank symbol on the tape in addition to a finite number of states, a finite set of input symbols, an initial state of automata, and a finite set of transition rules for moving from one state to another.
In this head is able to move in the right direction only. In two-way automata, the head is able to move in both directions.	In this, the head can move in both directions.
The Head is only able to read the symbols from the tape but can not write symbols on the tape.	The Head is able to read as well as write symbols on the tape.
It is weak as compared to Turing Machine.	It is more powerful than Finite Automata.
Designing finite automata is easier.	Designing turing machine is difficult and as well as complex.
The transition function in finite automata can be represented by: δ : Q × Σ* → Q	The transition function in turing machine can be represented by: δ : Q × T → Q × T × {L, R} where L and R specify the left and right movement of the tape head.
Finite state machines have lower computational power than the Turing machine.	Turing machines have more computational power than FSM.

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