Is the G in elliptical curve same for bitcoin and ethereum?
Yes Ethereum also uses the secp256k1 curve that is defined using the generator point:
Gx = 0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798 Gy = 0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8
If yes then why can’t we send bitcoin and ethereum to same public address?
For a number of reasons. Firstly, Bitcoin and Ethereum define addresses differently. Bitcoin uses the bech32 format starting
bc1 and Ethereum uses a hexadecimal string starting
0x. Secondly, Bitcoin addresses contain a checksum at the end of the address (to flag incorrectly typed addresses) whilst Ethereum addresses don’t. Thirdly, Ethereum only encodes the last 20 bytes of the public key into the address. Fourthly it is not just a raw public key that is encoded in a Bitcoin address. Bitcoin uses a scripting language “Script” that it uses to outline the conditions needed for the coins to move which generally includes requiring at least one signature associated with a particular public key. These conditions are baked into the address.
So yes don’t try sending Bitcoin and Ethereum to the same address, you will lose your coins.