有签名和没有签名的交易有什么区别?

当我将交易发送到 peer/transactions 我可以不带签名就寄过去。两个交易都被接受。有什么区别。

示例;使用asch js创建新的链/dapp

情形1:使用签名(和 transactionid ):

 function createDApp(options, secret, secondSecret) {
    var keys = crypto.getKeys(secret);

    var transaction = {
        secret: secret,
                type: 200,
        amount: 0,
        fee: constants.fees.dapp,
        recipientId: null,
        senderId: crypto.getAddress(keys.publicKey),
        timestamp: slots.getTime() - globalOptions.get('clientDriftSeconds'),
                args: [options.name, options.description, options.link, options.icon, options.delegates, options.unlockDelegates], 
                signatures: []
    };

    transaction.signatures.push(crypto.sign(transaction, keys));

    if (secondSecret) {
        var secondKeys = crypto.getKeys(secondSecret);
        transaction.signatures.push(crypto.secondSign(transaction, secondKeys));
    }

    transaction.id = crypto.getId(transaction);
    return transaction;
}

情形二:无签名

function createDApp(options, secret, secondSecret) {
    var keys = crypto.getKeys(secret);

    var transaction = {
        secret: secret,
                type: 200,
        amount: 0,
        fee: constants.fees.dapp,
        recipientId: null,
        senderId: crypto.getAddress(keys.publicKey),
        timestamp: slots.getTime() - globalOptions.get('clientDriftSeconds'),
                args: [options.name, options.description, options.link, options.icon, options.delegates, options.unlockDelegates], 
                signatures: []
    };

    return transaction;
}

两个事务都被接受(并创建一个新链)。那么什么是区别,什么是最佳实践?