Spiritual bliss is bliss of one's own Soul. It is transcendental bliss. It is independent of objects. It is continuous, uniform and eternal. It is enjoyed by the sage only.
Sensual pleasure comes out of emotion.
But bliss of the Soul is self-delight. It is the innate nature of the Atman. Pleasure is temporal and fleeting. Bliss is eternal and everlasting. Pleasure is mixed with pain.