They are different things, segwit makes for faster on-chain transactions while lightning network does off chain transfers like within a smartcontract.

my friend says ligtning network better than segwit, also he explain to me segwit and lightning network is different, im little confused how to lightning network implemented to blockchain

As far as I understand, SegWit is proposed to avoid increase block size. With SegWit activated, the data of each transaction is handle outside of each block and it can increase the block size with maximum of 2MB. However, even in case of all infrastructure implement 100% Segwit, the total throughput can be double in capacity which is still far beyond expectation for mass adoption. As for LN, it is better such that the transaction is occur off chain and near zero fee with instant confirmation. However, to implement LN, the Bitcoin chain has to set aside a prefunded BTC locked outside of mainchain. And this fund has to be constantly topped up to maintain the payment route for BTC. Such offchain fund is efficient for payments, but they would be exposed risk for hacker and more decentralized. For the purpose of scaling, LN is better but it is still not the perfect solution.

I think the lightning network is a centralized system. Similar to the role played by bank intermediaries in traditional transfer operations.

Is a fast payment network, payment and settlement separation.

I like the lightning network.

Both are necessary updates. Segwit fixes the expensive confirmation and because of the smaller sizes of transactions it also makes it faster up to some point and lightning network fixes the slow confirmation. This is necessary for everyday transactions like when you're buying a cup of coffee -- you dont want to wait a minute for it to be finalized. But lightining network isnt magic, it still has to communicate with the blockchain so it would still need segwit to store it. But if i had to choose i guess, i'd still go for lightning network. Some say it's centralized,  and somehow it is, but i think it's a nice trade off between decentralization and speed.  In the long run i think this is best as it would slow down the growth speed of the chain.

That's a funny way to put things, but I couldn't agree with you more.

As for exchanges using segwit, and although they seem to be taking forever to do so, specially big ones, like coinbase, I must say I understand their position. A lot has been said about their priority not being focused on their customers well being, and some even go further by saying that coinbase was almost deliberately "sabotaging" bitcoin by contributing to the high fees we were having. I honestly don't think they were doing that. They are one of the largest exchanges, and they need to approach these steps with caution, and with a lot of testing first, because any mistakes in their business would represent a huge blow in terms of profit, and actually a huge blow for bitcoin as well, since coinbase is seen as one of the safest exchanges out there.

If they would lose funds because they've decided to rush things, the impact on bitcoin would be huge, so I'm glad they took their time, and I do believe everything will turn out well. As for their priority I would say it's profit of course. They are running a business, and I don't expect that their main concern it the well being of their customers. So if implementing bcash trade first would give them more profit, I understand that this would be their priority. Nothing really wrong with that, and I think it's normal.