Landed Cost : is all cost (expenses) associated with purchase of Items\Articles\Products that a business may incur  to acquire that product. It could include transport, stocking fees, freights, customs and other charges depending on the industries. The functionality in GP allow to add the cost to the received inventory items and you could select to adjust the cost to include  additional expenses. see setup window below

Dynamics GP 2018 R2 Landed Cost
Dynamics GP 2018 R2 Landed Cost Setup

The Freight is the transport cost  to move a product from One company to a vendor or to the customer. In GP you could track that separately into different GL account.

The main big difference is that Landed Cost in Microsoft Dynamics GP allow you to add these extra cost to be reflected  in the inventory cost of item directly once you follow the landed cost processes. However the freight is more you track it separately  in another expense account.

some people opt for the freight and GL account expenses separately mainly because of the ease of the setup …

Dynamics GP 2018 R2
Freight Cost field

Hope that help and Contact us  for further Information and\or support