The finite automaton or finite automata theory has several classes that include the Deterministic Finite Automata (DFA) and the Nondeterministic Finite Automata (NFA). These two classes are transition functions of finite automata or finite automaton and they have some significant differences those are completely distinguishes the behavior of the finite auotmata. Here two separate tables those are clearly explain about the difference between the DFA and NFA and compare the performance of DFA and NFA on the behalf of various fields;
Difference between Deterministic Finite Automata and the Non deterministic Finite Automata ((DFA Vs NFA):
S. No.  DFA  NFA 
1.  For Every symbol of the alphabet, there is only one state transition in DFA.  We do not need to specify how does the NFA react according to some symbol. 
2.  DFA cannot use Empty String transition.  NFA can use Empty String transition.

3.  DFA can be understood as one machine.  NFA can be understood as multiple little machines computing at the same time.

4.  DFA will reject the string if it end at other than accepting state.  If all of the branches of NFA dies or rejects the string, we can say that NFA reject the string. 
5.  Backtracking is allowed in DFA.  Backtracking is not always allowed in NFA. 
6.  DFA can be understood as one machine.  NFA can be understood as multiple little machines computing at the same time. 
7.  DFA will reject the string if it end at other than accepting or final state.  If all of the branches of NFA dies or rejects the string, we can say that NFA reject the string. 
8.  DFA is more difficult to construct.  NFA is easier to construct. 
9. 
Comparison between Deterministic Finite Automata (DFA) and the Nondeterministic Finite Automata (NFA):
S. No.  Title  NFA  DFA 
1.  Power  Same  Same 
2.  Supremacy 
Not all NFA are DFA. 
All DFA are NFA 
3. 
Transition Function 
Maps Q → (∑∪{λ}→2^{Q}), the number of next states is zero or one or more. 
Q × ∑→Q, the number of next states is exactly one 
4.  Time complexity 
The time needed for executing an input string is more as compare to DFA. 
The time needed for executing an input string is less as compare to NFA. 
5.  Space  Less space requires.  More space requires. 
Time to attempt a Quiz Based on DFA and NFA questions.
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Question 1 of 14
1. Question
1 pointsCan a DFA simulate NFA?
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Question 2 of 14
2. Question
1 pointsWhich of the following statements is wrong?
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Question 3 of 14
3. Question
1 pointsWhich of the following statement is true about NFA?
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Question 4 of 14
4. Question
1 pointsWhich of the following statement is true about NFA?
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Question 5 of 14
5. Question
1 pointsIs it possible each NFA can be translated to an equivalent DFA?
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Question 6 of 14
6. Question
1 pointsNFA is used in a narrower sense too, what is it means?
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Question 7 of 14
7. Question
1 pointsIn which year NFAs were introduced?
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Question 8 of 14
8. Question
1 pointsNFAs were introduced by?
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Question 9 of 14
9. Question
1 pointsWhich of the following statement is true about NFA?
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Question 10 of 14
10. Question
1 pointsWhich of the following statement is true about NFA?
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Question 11 of 14
11. Question
1 pointsWhich of the following is not key motive to study NFA?
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Question 12 of 14
12. Question
1 pointsWhich of the following form can be reduced by DFA?
Correct
DFA can be used to reduce the canonical form (minimal DFA).
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DFA can be used to reduce the canonical form (minimal DFA).

Question 13 of 14
13. Question
1 pointsIn DFA a word is called accepted if and only if
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Question 14 of 14
14. Question
1 points____ and ____ were among the first researchers to introduce a concept similar to finite automaton in 1943.
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hi, i am archana
this website is very good!!!!!!
Hello Archana, Thanks for your appreciation.
why dfa does not accept same latter transition ?
please explain with example.
Simple and very useful
I want the difference between finite automata, transition state, NFA….