Sure thing, no problemo.
The top of HDD and SSD life is greatly researched! There's A LOT of research online.
To answer that question, there's a few things that one needs to look at and understand this topic: general lifespan of drives, voltage, and writing/reading formats.
Lifespan: Though there are some outliers, SSDs generally have a shorter lifespan when compared to a HD when both have been run normally. So, right off the bat, the the SSD is expected to have a worse life span. SSD life is a HEAVILY investigated issue for all drive manufacturers. You don't want to start off on the wrong foot.
Voltage: On a platter/disk drive, the disk is the part that stores the data, and it is a physical unit that does not have any electricity running through it. No matter how long you run it, the disk itself can't be damaged or corrupt until an outside force acts on it. The platter/disk itself(not the whole drive unit) is the most reliable aspect of any storage unit ever made because its solid and robust. On a solid state drive, there are "flash"(for simple terms) chips on a board that are used to store the data. The only way to access that data is to run electricity through it. Though there is promise of future carbon and other tech for storage, the current storage chips degrade the more electricity is run through them during write and read sessions. One way to get faster chips is to up the voltage and speed. The faster the SSD, the quicker it can wear out flash storage. This is where the MTF(Mean Time to Failure) figure comes from. It's is usually shown along with an average daily write/read rating that's usually around ~5Gbs of data per day. 5Gb might be a lot for some, but it can be nothing for some people like myself.
So, you're probably asking what does this have to do with the question?
Let's take a look at writing and reading formats.
It all has to do with how a platter/disk drive writes data compared to a solid state drive!
A platter/disk drive will write data in sequence as it comes. Only way to prevent this is by creating separate partitions, and handling files on your own. This method of writing data on a disk can be slow, especially when you have to overwrite data from a previous data locations because the arm has to move to the exact position of the stored data. Even though this system is slow, it is very reliable, with drives easily lasting over a decade.
With a solid state drive, the storage units of that drive are comprised of multiple flash chips, and each chip has multiple storage sectors. There's a pathway to go to each sector. For example, let's say your SSD has 4 flash chips, and each flash chip has 8 sectors in it. This means the SSD can choose to write data in 32 different sectors. With each sector comes a different pathway. So there will be 32 different pathways it needs to know when writing and reading data. The SSD automatically allocates where the data is written, and does so in order to maintain peak average performance speeds. Smart allocation of data is what leads to minimal voltage running through the chips. It can prioritize data and spread them across those 32 sectors. The more sectors to gb ratio you have on an SSD, the cheaper it will usually be because speed is the number 1 reason for an SSD to be expensive. It's the same analogy with ram sticks where an 8gb stick with 8x 1gb chips is more expensive than an 8gb stick with 16x 512mb chips. The 8x1 can have 32 sectors, while the 16x512 has 64 sectors to manage and will be slower.
By now, you probably should be able to put something together.
When you copy/clone an HDD on an SSD, you are forcing that data to be cloned in a writing sequence that is used by the HDD, and is not normal for an SSD. The data will be written randomly across sectors, and it will not be efficient. This will cause the SSD to "hunt" for data because it is literally scattered across the flash modules. This causes the chips to have spikes in voltage and a drastic increase in daily read/write uptime. That 5gb/day average can be very easily surpassed if data on an SSD is not efficiently handled from the beginning.
When cloning an SSD to HDD, you are cloning the storage sequence that makes an SSD quick, and forcing that onto a single(multiple disks is even worse!) disk that rotates. You are cloning a scattered plot of data and putting it in sequence on a disk while it is out of order. If you do this, you will notice your HDD always running at high RPMs, and jumping a lot because the data is not in the order designed for an HDD to run efficiently. Brown outs and arm movement issues are some of the common causes of disk failures. You want the arm to move as less as possible to prolong the HD's life.
That's why they say, if you are upgrading to an SSD from an HDD, do a fresh install. You just don't hear the reverse because no one goes from SSD to HDD
Theres some other stuff too, but I don't think they are as important.
I personally don't ever do clone copies of drives. I have run many backup drives, as seen below in my picture of my Powerbook project. If I have to move data from one drive to another, I will do it manually myself. Corrupting data from copying is SOOOOOOO easy to do, and every file I have is very important. If I do it myself, I at least feel a little better knowing I moved the files separately and they are being stored and handled individually by the new drive on its own.:
