any ways to imrprove defence???


When an attack is positionally justified, it may be impossible to defend directly. When direct defense IS possible, it's often very technical and difficult. If you are only defending, they can rearrange their attacking pieces over and over and wait for you to make a mistake.
After the opening phase is over, ideally you'll have your own trumps to counter balance his attacking ideas. So then, in some cases for example, you might have to sacrifice material to defend your king, but your advantage is so strong on the other side that he will have to sacrifice back to e.g. prevent a pawn from queening.
One of the basic ideas is that an attack on the flank is met with a counter attack in the center.
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Gambit openings are especially challenging if you don't know the opening. Be sure to review your opening choices after the game. Using a database, wiki, or book (like MCO) for reference can help you discover what the various options are (some are easier or will fit your style better than others).
My personal approach would be to try to make the game more quiet, taking the fun away from the player who loves to attack. But if your goal is to win at least once, then you're probably better off learning the sharpest lines, make a big mess of the position, and wait for him to blunder and then you'll have your chance.

So in the king's gambit a way to avoid a messy position would be something like1.e4 e5 2.f4 Bc5 3.Nf3 d6
but if you want make things complicated and increase his chances of blundering, then it would be for example 1.e4 e5 2.f4 exf 3.Nf3 g5
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In the benko you could decline benko type positions with 1.d4 Nf6 2.c4 c5 3.Nf3 and if 3...g6 just keep developing normally 4.Nc3
But if you want to make a mess there's a line 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb a6 5.f3 which is a good line that can also be very dangerous for players who don't know theory.
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For your development as a chess player, it's generally better to play the calmer lines. If you want to win 1 game out of 100 against a much stronger player then you'll generally want the wild lines.

But anyway, IMO a way to improve defense is to learn how to attack. If you can't see the attacking idea that your opponent is aiming for, then it's impossible to defend against it (unless you get lucky and notice it through pure calculation).
Also, as you attack or at least study attacks, you learn different types of defensive ideas that impede attacks. Like controlling a certain line (diagonal, rank, file) or square. Closing off certain lines, trading off attackers, running away with the king, these sorts of things.

Keres had a great middlegame book in which he focuses half of the book to defense. But I think it is to advanced for you (guessing by your chess.com's rating).
If you are interested in it it is "The art of the Middlegame".

To beat a better player you have to improve your overall chess. A maybe quick fix to your problem would be to not run into his game and learn how to correctly decline gambits (b6 against the Benko is a beatiful way to decline it).
But again, the better player should always win regardless of the opening.