No, it's not the same when sending an email between SCRYPTmail, ProtonMail, and Gmail
If you choose to send an email unencrypted, the copy on SCRYPTmail and ProtonMail will be encrypted on their server, but not the copy on the Gmail servers.
If you choose to send a message notification causing the original email to stay on the encrypted service provider servers, forcing the recipient to view it with a shared pin number, then all copies of the email are encrypted.
When sending between the encrypted providers, the notification system will still need to be used until there is better cooperation between the encrypted email services.
Depending on how you are looking at the question, it's possible that SCRYPTmail and ProtonMail are the same for your purposes.
What requirements do you have right now? How much effort do you want to put on your recipients?