In blogger new interface there is only one size for images to upload, in old there were three sizes. If you want to upload in small size like in old interface there is a trick to do that.
Go to new post, click HTML and click on insert image. Now you will see the old interface uploading images with 3 sizes.
To upload multiple images at once use the DragDrop mozilla addon. click here to get the addon
Go to new post, click HTML and click on insert image. Now you will see the old interface uploading images with 3 sizes.
To upload multiple images at once use the DragDrop mozilla addon. click here to get the addon