With the Israelites going through the desert for 40 years, trying to get to the promised land & with all their troubles & disobediences & grumbling, I always thought that our life here on earth was the same. Is our promised land & Heaven the same?

Very much our promised land and heaven are the same. Interestingly, at least in the NIV, the phrase “promised land” is only used once, referencing Abraham (from the Old Testament) in the New Testament book of Hebrews—in the “faith hall of fame” of Hebrews 11: By faith Abraham, when called to go to a place he would later receive as his inheritance, obeyed and went, even though he did not know where he was going. By faith he made his home in the promised land like a stranger in a foreign country; he lived in tents, as did Isaac and Jacob, who were heirs with him of the same promise. For he was looking forward to the city with foundations, whose architect and builder is God—Hebrews 11:8-10. The promised land we have to look forward to, of course, is heaven, and Paul made it very clear one thing that’s new once we surrender to God through Jesus Christ: We have a new home. As he said to the church at Philippi, [A]s I have often told you before and now say again even with tears, many live as enemies of the cross of Christ. Their destiny is destruction, their god is their stomach, and their glory is in their shame. Their mind is set on earthly things. But our citizenship is in heaven. And we eagerly await a Savior from there, the Lord Jesus Christ, who, by the power that enables him to bring everything under his control, will transform our lowly bodies so that they will be like his glorious body—Paul, Philippians 3:18-21. That heaven is our final, ultimate destination is a promise based on Christ’s words to the disciples in the Upper Room, just a short time before His arrest in Gethsemane and all that followed: In my Father’s house are many rooms; if it were not so, I would have told you. I am going there to prepare a place for you. And if I go and prepare a place for you, I will come back and take you to be with me that you also may be where I am—Jesus Christ, John 14:2-3. What is so amazing is just the simple fact that Christ wants us with Him. He wants the relationship He has with each and every Christian to become perfect and eternal. And what a future it is, starting with this: Brothers, we do not want you to be ignorant about those who fall asleep, or to grieve like the rest of men, who have no hope. We believe that Jesus died and rose again and so we believe that God will bring with Jesus those who have fallen asleep in him. According to the Lord’s own word, we tell you that we who are still alive, who are left till the coming of the Lord, will certainly not precede those who have fallen asleep. For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever. Therefore encourage each other with these words—Paul, I Thessalonians 4:13-18.
It is also important to keep in mind that the Israelites’ 40 years of wandering in the wilderness was divine punishment for their rejection of all of God’s promises that He would indeed give them the Promised Land (see Numbers 13-14). When they heard the spies tell them of the large, scary inhabitants of the land that awaited them, they said, “No,” despite the fact that Joshua and Caleb (two of the 12 spies who had seen the land for themselves) reminded the people that God was with them and, if that was so, there was no question that the land was theirs for the taking. As a result of their rejection, God kept them in the wilderness until that entire generation of adults that had rebelled against Him died out in the wilderness, leaving behind generations ready and willing to follow His lead into Canaan. For us, our time on earth is simply to be about the work of the Master—sharing His love, telling His stories, offering His salvation. As long as we live, we’re here for the Master. In heaven, our Promised Land, we’ll live with the Master—forever! Amazing!