There are difference between deposit and part payment in a formal contract of sale of Land.
While deposit is a minimal sum paid with the intention to show that there is an interest to contract of sale of land.It is an insufficient amount paid compared to the total sum for the sale of land.But part payment is where a substantial sum has been made for the valid contract of sale of land.
Secondly a deposit without a condition to the contrary, can be refunded but for part payment, it cannot be refunded as the contract has been deemed to have taken place.
Thirdly,for payment of part payment the Law presume that the contract of sale of land has been sealed and finalized and Thus the parties cannot rescind.However for deposit, the parties can rescind the contract as the contract of sale of land is not yet finalized.