If the images are of the same size, and of the same magnification and fairly well aligned (a doubtful scenario in a real world situation) then you can subtract the images and look for blobs of non-zero. Untested code:
% Get the difference image.
diffImage = imabsdiff(double(image1), double(image2));
% Get the max in any of the color channels
diffImage = max(diffImage, [], 3);
% Threshold to find significant differences.
mask = diffImage > 5; % or some value.
% Throw out any blobs less than 50 pixels in size (they're noise).
mask = bwareaopen(mask, 50);
imshow(mask);
% Make measurements of area and centroid.
props = regionprops(mask, 'Area', 'Centroid');
allAreas = [props.Area]
centroids = vertcat(props.Centroid)
