A major difference between a trust and will is that a will must go through probate, whereas a trust can avoid probate. The heirs can avoid the lengthy process of probate when the assets are put through a trust. Since there is no probate process involved, there is no display in the distribution of the assets. Besides, with a trust, you can avoid estate transfer tax as well.
A will is a public and court-controlled document, while a trust is a family-controlled and private process.
One major disadvantage of having only Trust is that the assets can be distributed to your children only after attaining a certain age. Until then, it is controlled by the trustee. That is why reliable wills and trusts solicitors will tell you that it is advisable to use both will and Trust for your assets.