This may help you to understand this better my friend.

Security tokens bridge the gap between the traditional financial sector and the blockchain framework; it’s one of the reasons banks have initiated the integrated Blockchain frameworks in their system. Issuing security tokens allows investors to raise funds through a thoroughly regulated digital share of its equity, asset or part of the revenue.

The key difference between Security Token and Equity Token is that in the security token, an asset like real estate, gold etc. are used as collateral. However, in the case of Equity tokens, the shares of the company are diluted into tokens.