Heart-felt = (of a feeling or its expression) deeply and strongly felt; sincere.

• Please accept my heartfelt apologies/thanks.
• I would like to express my heartfelt gratitude to all the fishermen who volunteered in the rescue operation.
• Louis expressed his heartfelt condolences to the bereaved family.

Hearty = cheerful, spirited, enthusiastic etc( often loudly expressed)

• Louis extended a hearty welcome to the guests.
• A hearty laugh/handshake.
• Hearty congratulations.

(2)  (of food) wholesome and substantial.

• We ate a hearty breakfast before we set off.