What is the difference between 魂 and 魄? Maybe this is a religious technical question and therefore a bit tricky. In English, soul and spirit are used more or less interchangeably, although their origins are dissimilar.

spirit: mid-13c., "animating or vital principle in man and animals," from Anglo-French spirit, Old French espirit "spirit, soul" (12c., Modern French esprit) and directly from Latin spiritus "a breathing (respiration, and of the wind), breath; breath of a god,"

soul:"A substantial entity believed to be that in each person which lives, feels, thinks and wills" [Century Dictionary], Old English sawol "spiritual and emotional part of a person, 

In Chinese, is there a difference between 魂 and 魄？

魂: soul, spirit (We have 3)
 魄: soul, spirit (we have 7)

道家谓人有三魂

三魂：1.道家谓人有三魂：一曰胎光，二曰爽灵，三曰幽精，见《云笈七签》卷五十四。

道家谓人有七魄：

七魄：1.道家谓人有七魄，各有名目。第一魄名尸狗，第二魄名伏矢，第三魄名雀阴，第四魄名吞贼，第五魄名非毒，第六魄名除秽，第七魄名臭肺，见《云笈七签》卷五四。

Just got this phrase from reading 西游记：道士吓得三魂丢了七魄 which I would simply translate as 'very frightened, scared witless, frightened out of his mind'
This question is more advanced.

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In short, 

魂 is more related to the 陽 Yang side (the male, the bright, the sun side) of the spirit or soul.  

魄 is more related to the 陰 Yin side (the female, the dark, the moon side) of the spirit or soul.

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You may find the following texts valuable.

1) 道教原始的生命观认为，魂和魄一个属阴，一个属阳，一个主静，一个主动。阳魂就是思想，主动，是注意力，是对身体接触到外世界之后的第一反映，阴魄就是不变化的本源，主静，是对思想的承载，是一切万有的实质和内含。宇宙天地万物的总依赖。所以魂和魄之中，阴魄是体，阳魂为用。-- from www.zhihu.com/

2) 在中國哲學之中，魂魄陰陽對反，魂為陽性精氣，魄為陰性精氣

3) "Within this ancient soul dualism tradition, every living human has both a hun spiritual, ethereal, yang soul which leaves the body after death, and also a po corporeal, substantive, yin soul which remains with the corpse of the deceased. Some controversy exists over the number of souls in a person; for instance, one of the traditions within Daoism proposes a soul structure of sanhunqipo 三魂七魄; that is, "three hun and seven po". The historian Yü Ying-shih describes hun and po as "two pivotal concepts that have been, and remain today, the key to understanding Chinese views of the human soul and the afterlife.""

4) If you know the Naruto story, the author also used the similar idea of 陰 Yin side and 陽 Yang side of souls as the two dual souls of the Nine Tail beast. See also the Yin-Yang release and more.