Transaction fee is based on only "transaction size" ? or depends on "transaction amount" as well? In the Bitcoin, transactions fees are different in value. Now the question is that this transaction fee is based on only "transaction size" ? or depends on "transaction amount" as well ? 
For example, consider transactions A and B have same size. However, amount of transaction A is 2 bitcoins and amount of transaction B is 1 bitcoin. In this case, these two transactions have equal fee ?
First, when we quote a "Bitcoin transaction fee", we will usually quote one of two numbers:

Consumers care about the total fee.This is the total fee that you're paying in a transaction, such as 10,000 satoshis or 0.0001 bitcoins. This is probably the most important number for consumers as they only care about the fees associated with their particular transaction.Miners care about the fee per byte (or kilobyte).This is the total fee divided by the number of bytes in a transaction, such as 40 satoshis/byte or 0.0004 bitcoins/kilobyte. This is the most important measurement for miners. The reason is that they use this to decide whether to include your transaction in the blocks they attempt to produce, as they can only include about 1 million bytes of transactions in their blocks. As such, they prefer to include transactions that pay more fee per byte.

It's important to note that the total bitcoin amount of your transaction doesn't matter for the purposes of fee calculation! For example, if your transaction is 250 bytes, you'll have to pay the same fee whether you're transferring 0.001 bitcoins or 1 million bitcoins.

For a transaction that you've already sent, you'll find either one of the numbers above or both numbers above on a block explorer.  For transactions you haven't sent yet, you probably want to find the best fee-per-byte to ensure your transaction confirms quickly.