I have brain lesions, same as "tumor"?

Not necessarily : A brain lesion may represent a benign or malignant tumor or may be inflammatory, hemorrhagic or ischemic(lack of blood supple to area as in a stroke). Obviously, if you have brain lesions, you should be under the care of a qualified physician.

Nope: lesion just means something different - does not imply a tumor. Often there are "UBOs" = unknown small bright objects. Lesions could be inconsequential or could be serious like an infection or inflammation or something neurological or a tumor. Your doctor who did the test can better explain.

Not the same: Brain lesions can be anything seen on an MRI or ct ranging from old trauma, old strokes, signs of multiple sclerosis, infections, abnormal vessels (just about anything). We usually don't call tumors 'lesions'...We call them tumors. With technology today, we see lots of stuff on mri's that we aren't actually sure what it is, so we call them 'lesions' and watch them.