Is it possible that the private key generated from a passphrase by a deterministic wallet, gets also generated by non-deterministic wallet from a random number ? I understand the negligibility of the collision chance factor. What I am trying to understand here is if it is theoretically feasible at all !!!
A collision is possible, but the range of values used for a wallet seed is so large that the chances of a collision is negligible -- assuming that the random number generator actually works well.
This.
For your info, seed used in Electrum is 128 bits, so there are a total of 2^128 possible choices of the seed.
Bitcoin address and private keys are 160 and 256 bits on the other hand.
Is it possible to have a collion? Yes, but the probability is extremely extremely extremely small.
Is electrum a deterministic wallet ?
AFAIK, Electrum is a deterministic wallet, and you can recover all your private keys with only the seed.