Klaviyo is an email marketing platform.

Mailchimp helps you design email newsletters, share them on social networks, integrate with services you already use, and track your results. It's like your own personal publishing platform. wikipedia.org

"Marketo is a Marketing Automation solution encompassing B2B marketing & lead management, Email & campaign management, Personalization across channels and marketing Budget & calendar Plan." wikipedia.org

Email marketing is directly marketing a commercial message to a group of people using electronic mail email. wikipedia.org

PSD to Mailchimp template conversion is the process of converting an Adobe Photoshop file (.psd) into an HTML email template for use with the email marketing service MailChimp.

PSD to HTML conversion is the process of converting a PSD (Photoshop document) template to functional HTML web page.

HyperText Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages. wikipedia.org

Pardot is a business-to-business marketing automation software.

Email marketing is directly marketing a commercial message to a group of people using electronic mail email. In its broadest sense, every email sent to a potential or current customer could be considered email marketing. It usually involves using email to send ads, request business, or solicit wikipedia.org

Web development is a broad term for the work involved in developing a web site for the Internet (World Wide Web) or an intranet (a private network).