Ireland is the name of the island on the left.... Great Britain is the island on the right.
"Ireland" is also used instead of saying "Republic of Ireland"... which is the country that is not coloured in for this map.
The coloured in parts are what constitutes as The United Kingdom (the full name of which is "The United Kingdom of Great Britain and Northern Ireland")
England (not named on the map, but is split into 8 parts instead), Scotland, Wales and Northern Ireland are also thought of as seperate countries in a way, even though they are not officially (you don't get seperate passports) It is similar to how Holland is sometimes though of as a country when it is just a part of the Netherlands.