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 :
- Input
- Output
- States of automata
- State relation
- 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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