Why there are significant differences in current BTC value between different exchanges.
Supply and demand. Some local country-based exchanges that are not accessible to the public and thus are less influenced by global buying or selling pressures. If you're thinking it, yes, in these cases, locals can actually do arbitrage and profit from the value differences. However, because when such happens, the values differences usually even themselves out in the end. Consider yourself lucky if you were able to do arbitrage before the gap closed.
The arbitrage are highly risky because the prices will change before we withdraw our funds from exchanges so we will lose money in form of network fee and transaction fees.But I noticed that the LBC offers better price always so if you have high capital then you can buy on coinbase and sell it on LBC.