The Giver is the new name for the Receiver of Memory. He becomes the Giver when Jonas is selected as the new Receiver. Now he must give his memories to Jonas.
Sameness is the guiding principle of the society they live in. The idea is, as you might guess, that people should be pretty much the same as one another. They should not really have strong feelings and they should not feel close ties to anyone in particular. Everything that can be controlled will be in the society will be.
This includes the weather. They control the climate so they can have as much Sameness as possible.
In the book "The Giver" climate control means that there are no weather changes. Jonas' first experiences cold as the first memory that the giver transfers to him. He feels his skin tingle and then feels the cold on his tongue. When the community made changes they decided to do away with anything that could create discomfort. One of the things was weather.
Sameness becomes awareness for Jonas when he begins to experience color. The color red is his first color that he sees. He learns that once people were different but now they are all the same. However, when he has some of the new memories he can see his friend's red hair. Despite having sameness meaning al the people wear the same color and style clothing with the exception of the year of their aging, some might have buttons on the back of their shirts or another age group wears bows, there is a different in Jonas and Gabriel's eyes. The book talks about them as having eyes which are lighter than the others.
The Giver was once the holder of the memories. He calls himself the Giver when he passes his memnories to Jonas. Jonas in the same way gives some of his memories to the baby Gabriel.