I wouldn't compare it to black tiger since because of the rift between projectiles and close up combat.
Its not even a comparison, its a straight port that was customized to Son Son.
They share the same unique jumping/climbing gameplay, long attack weapon, enemies/obstacles(and BT has some unique enemies), level layouts(slopes, dungeons..), powerups/items, Zenny & shops... all anyone has to do is play a couple levels of one and then the other.
I just wish I knew about Son Son II back in the day and always wanted a home version of Black Tiger.
It killed me than in the flyers and/or manuals of early Capcom NES games, they listed Black Tiger as coming soon. For years I was sure that there was a Famicom version out there somewhere.