The difference is the number of shares outstanding.
For Alphabet is 745 millions shares.
For Microsoft 7710 millions.
For Apple 4443 millions.
These above are the most recent numbers I could find, anyway as you can see Microsoft has about 10 times more shares outstanding than Alphabet therefore the price is about 1/10.
Otherwise you can determine by dividing the market cap by the current share price.
The simple answer is stock splits. Google has only had one where as apple as an example has had many. In fact it had a 7:1 split last time to reduce its share price. This means lower share price but more outstanding shares. Which is what the previous poster mentioned.
Share Price x Number of Shares Outstanding = Market Cap(1tn valuation in this instance)
Each company can issue as many shares as they please, therefore the share price being higher or lower than another is meaningless. A more comparative measurement is P/E or PEG Ratio(if companies are in different sectors)