Difference between SHA1 and SHA2

1. SHA1 (Secure Hash Algorithm 1) :
SHA1 is a cryptographic hash function which is designed by United States National Security Agency. It takes an input and produces a 160 bits hash value. Further the output produced by this function is converted into a 40 digits long hexadecimal number. It is a U.S. Federal Information Processing Standard. It was first published in 1995. It is successor to SH0 published in 1993.
Example:

Data : Geeksforgeeks
SHA1 : bc7623b7a94ed3d8feaffaf7580df3eca4f5f5ca 

2. SHA2 (Secure Hash Algorithm 2) :
SHA1 is also a cryptographic hash function which is designed by United States National Security Agency. It is constructed using the Merkle-Damgard structure from a one-way compression function. The compression function used is constructed using the Davies-Meyer structure from a classified block cipher. It was first published in 2001. It is successor to SH1.
Example:

Data : Geeksforgeeks
SHA2(256) : 86d755349c6b9f95f365c6ffe7734f25bf2b00cabe8c6bc5f2b8b746c1aac332 

Difference between SHA1 and SHA2 :

SHA1	SHA2
It is a cryptographic hash function designed by U.S National Security Agency to replace SH0.	It is a cryptographic hash function designed by U.S National Security Agency to replace SH1.
It was published in 1995.	While it was published in 2001.
It produces 160 bits hash value.	It produces 224, 256, 384 or 512 bits hash value.
It is successor to SH0 and predecessor to SH2.	It is successor to SH1 and predecessor to SH3.
It is less secure.	While it is more secure.
Its structure is based on Merkle–Damgard construction.	Its structure is based on Merkle–Damgard structure with Davies–Meyer compression function.
SHA1 certificates are not reliable.	SHA2 has more improved certificates.
It generates smaller hash.	While it generates larger hash.
Hash generated by SHA1 is weak.	While hash generated by SHA2 is strong.
It is not widely used now-a-days.	While it is used widely.