If you see over the deficit and compare them in Upper motor neuron, you may find the difference.

Upper Motor Neurone Lesion

Drift of Upper limb
Weakness with Characteristic Distribution
Increase in the tone of spastic type
Exaggerated tendon reflexes
An extensor plantar response
Loss of abdominal reflexes
No muscle wasting
No electrical excitability of muscle

Lower Motor Neurone Lesion

Weakness
Wasting
Hypotonia
Reflex Loss
Fasciculation
Contractures of muscle
Trophic changes in skin and nail


So generally functional movement are diificult to get in a sense that effector organs not ready to respond well in LMN Lesion. Examples are cases of poliomyelitis, peripheral nerve injuries, etc. However, in UMN lesions after a pleatue phase, a recover patten or motor control start to develop depending upon the extent of lesion. However, there are exceptions and extent of lesions that are debatable.