"The two games have absolutely nothing in common," Appiah told reporters at his pre-match media briefing at the Nelson Mandela Bay Stadium on Friday.
"Only four or five players from that side are here - but the players who are here are tougher, stronger and far more confident.
"I believe Cape Verde is a very strong team now. I still think we will beat them, but it will not be easy."
Appiah came in for some criticism earlier in the week when he said he would rather face tournament favourites Ivory Coast than Cape Verde at this stage - a comment that raised some eyebrows among his domestic media.
But he explained what he meant on Friday: "The reason for thinking that is because I know every player in the Ivory Coast side and I know what to expect from them.
"Cape Verde, on the other hand, are coming to the game a very strong team but with no pressure on them at all.
"They are not expected to win, and so they have nothing to lose and that is a fear for me. Of course Ivory Coast is a dangerous opponent, but you know how to plan for a familiar opponent under pressure like yourself."
Appiah is certainly a man under pressure.
Ghana, who won all of their four African titles between 1963 and 1982, are desperate to end their 31-year wait for their fifth crown.
They were the only African side to advance from the group stage of the World Cup in South Africa three years ago when they were a penalty kick away from the semi-finals, and are currently ranked 26th in the world.
Ghana came through the group phase with two wins and a draw and apart from allowing the Democratic Republic of Congo to salvage a 2-2 draw after Ghana had led 2-0, they have looked sound enough.
Appiah was not too happy they took their foot off the pedal after going 3-0 up against Niger early in the second half in their final group match, but explained he knew why it happened.
"It's normal - if you are leading 3-0 you will be more relaxed but my players started playing the ball around in their own half and gave away possession and we cannot do that against Cape Verde. They have the players to punish us."
On paper, Ghana against Cape Verde is a mismatch but the four-times champions are not taking victory for granted.
"No-one is underestimating Cape Verde for a moment. If we do that, we will lose and you know where you find yourself then," defender John Pantsil told the conference.
"We know it is going to be tough, but we are ready to go, and like the coach said, we are confident we can make it through."
Appiah said everyone in the squad was fit, confirming that influential midfielder Mubarak Wakaso had recovered from his knee injury and could even start in midfield alongside the highly impressive Christian Atsu, who replaced him against Niger on Monday.
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