Difference between External Fertilization and Internal Fertilization (External fertilization vs Internal fertilization)

Fertilization is defined as the fusion of male gamete (sperm) with a female gamete (an ovum or egg) to form a zygote during sexual reproduction. 
Two types of fertilization: External and Internal.

External fertilization vs Internal fertilization

External fertilization	Internal fertilization
The fusion of male gamete and female gamete occurs outside the body	The fusion of gametes occurs inside the body.
Both individuals discharge their gametes outside the body.	Only male discharges sperms into female genital tract.
Development occur outside the body.	Development occurs inside the body.
External fertilization occurs in Fish, Toads, and Frogs (Amphibians).	Internal fertilization occurs in Human, cattle, Birds etc. The site of fertilization in human beings is in the fallopian tube of female reproductive system.

Advantages and Disadvantages of Internal Fertilization and External fertilization

Internal fertilization Advantages: 

• More offspring survive due to protection of embryo and parental care.
• High chance of successful fertilization. 

Internal fertilization Disadvantages:

• Requires more energy to find a mate.
• less number of offspring produced.
• Large investment from female parent, may leave her vulnerable. 

External Fertilization Advantages: 

• Little energy needed to find a mate.
• Many offspring produced.
• Offspring not in competition with parents.

External Fertilization Disadvantages: 

• Many gametes do not survive or are not fertilized.
• Zygotes and embryos are unprotected. 
• No parental care mean many offspring do not survive to adulthood.