Why does the Royal Navy White Ensign look so similar to the English Cross Of St.George when it is the British Navy?

"The Royal Navy was organized into three squadrons, which flew either red, white or blue ensigns with a Saint George's cross canton. The oldest was the Red Ensign that had been a general flag from about 1620, even before the squadron system was introduced in 1630. In 1674, the Red Ensign was also approved as the merchant ensign. In 1701, an overall St George's cross was added to the white ensign to distinguish it from the French flag, which was mainly white. The "1606 Union Flag" replaced the "Saint George's Cross" in the canton in 1707, only to be replaced by the "Union Jack" in 1801. To avoid confusion, Nelson used the White Ensign for both the White and Blue Squadrons at Trafalgar in 1805, and in 1864 an Admiralty Order in Council ordered the Royal Navy to discontinue using the Red and Blue Ensigns completely, and made the White Ensign the only official Royal Navy ensign."

http://www.loeser.us/flags/english.html

That's not a proper answer. Quoting Wiki is not a polite way to give an answer. There is a possible problem with the definition between a flag and an Ensign

The RN White Ensign is a flag, not a signal. Read the below link for the history.