The role of the Backoffice is to organize Clearing and Settlement.

The Backoffice is providing failback operations, when trading operations fail (Back is for Backup)

The Backoffice is processing transactions. 

The Backoffice is part of the Risk Management of a banking institution.

The Backoffice is a management layer in banking operations, which deals with transactions.

The Backoffice is responsible for trading operations.

The Backoffice is term to describe a number of departments which provide support for trading operations.

The Backoffice is organizing pre-trade check before execution. 

Pre-trade describes all operations after execution, but before Clearing and Settlement.

Pre-Trade is describing Bid and Ask Quotes in the orderbook.

Pre-trade describes all operations after execution of a trade. 

Pre-trade describes all operations before execution of a transaction.

Buy-Side is an investor willing to Buy. Sell-Side is an investor willing to Sell.

Sell Side describes all financial companies which are selling Financial Services to the Buy Side (like market data, brokerage, execution, risk management). 

Dealers receive orders but they are allowed to trade on this information, on their own account.

Brokers and Dealers receive instructions to buy, sell or modify orders from their clients.

Dealers provide Sell-Side services to investors.

Dealers provide buy side services to investors. 

There is no difference, both do the same. It's just different names.

Brokers provide Buy-Side services for investors.

The investor is legally responsible to document all trade information.

The investor initiates the transaction and creates the order to Buy/Sell. 

The investor is the beneficiary of a transaction (he receives the asset, or the money)

The Investor can be a company, a mutual fund, or a hedge fund, a public institution or a private invidual.

The investor is responsible for clearing and settlement of his transactions.

The investor decides to Buy or Sell a financial instrument.

The Front Office is responsible for clearing and settlement of transactions.

The Front Office is monitoring open orders to be able to react (modify, cancel, delete) new orders on the exchange.

The Front Office receives instructions to trade from Investors and sends these to Brokers/Dealers.

The Front Office receives instructions to trade from the Middle Office.

Brokers and Dealers execute trade instructions on the exchanges. 

The Front Office does not include specialized Broker and Dealer services.

The Front Office only monitors trade executions, It cannot trade by itself.

The Front Office can simulate different trading situations to find the best possible execution price

The Front Office is a top management layer in investment companies, above the middle office and the back office.

The Front Office is the place where banks or institutions actually trade.

The Front Office is the middle management like CTO, CIO, COO. 

The Front Office is providing IT support for Middle Office and Back Office.

The Front Office in a bank is the department with First Contact to clients. 

In the Front Office the traders are executing trades.

After a sucessfull trade the Front Office is sending all information to the Backoffice for settlement, and clearing.